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1. Command Description Page MODE MODE Set query operation mode 42 OPRANGE OPRANGE Set query output voltage range 46 SRANGE SRANGE Set query scanning voltage range 61 SPEED SPEED Set query scanning speed values 60 OUTBEAM OUTBEAM Set query OUTBEAM configuration 50 INBEAM INBEAM Set query INBEAM configuration 38 GAIN GAIN Set query preamplifier gain table 35 OFFSET OFFSET Set query electrometer input offset correction 45 BEAMCHECK BEAMCHECK Set query beam detection parameters 28 INHIBIT INHIBIT Set query hardware inhibition settings 41 SET SET Set query operation flags 56 CLEAR CLEAR Clear query operation flags 30 AUTOTUNE AUTOTUNE Set query autotune options 26 AUTOPEAK AUTOPEAK Set query autopeak options 25 AUTOBEA Adjust input channel ranges 24 AMPLITUDE AMPLITUDE Set query amplitude of oscillation 23 FREQUENCY FREQUENCY Set query oscillation frequency 34 PHASE PHASE Set query oscillation phase 53 TUNE Start tuning sequence 65 GO Start regulation 36 STOP Stop operation 63 PAUSE PAUSE Set query pause mode 51 PIEZO PIEZO Set query output voltage 54 PEAK PEAK Set query peak parameters 52 SLOPE SLOPE Set query response function slope 59 SETPOINT SETPOINT Set query setpoint value 57 TAU TAU Set query regulation time constant 64 OSCIL OSCIL Start que
2. NAME Main Monochromator 43 NOECHO Cancel echo mode Syntax NOECHO Description Switches the echo mode off See the ECHO command for more details Example Command NOECHO 44 MoCo User Manual OFFSET 0FFSET Set query input offset correction Syntax OFFSET INBEAM OUTBEAM lt offsCorr gt Description Sets the magnitude in mV of the correction used to cancel the input offset voltage of the internal current amplifier of the selected channel When using beam monitors with low output resistance current sources like large area photodiodes in photovoltaic mode the input offset voltage appears as a burden voltage that induces an extra current component that adds up to the beam monitor signal WARNING These parameters does not correct for signal offsets in the input sisgnals This setting is part of a calibration procedure and should normally not be changed by the user Syntax 2 OFFSET Answer lt inbeamOffsCorr gt lt outbeamOffsCorr gt Description Returns the input offset voltage correction of the INBEAM and OUTBEAM channels in mV Examples Command Command Command Answer MoCo User Manual OFFSET INBEAM 0 153 OFFSET OUTBEAM 0 023 OFFSET 0 153 0 023 45 OPRANGE 0PRANGE Set query output voltage range Syntax OPRANGE lt Vmin gt lt Vmax gt lt Vsafe gt Description Sets the o
3. If no address has been set returns an empty string Returns the status and type of the secondary communication port The status indicates if there is another isgdevice connected to the secondary port by the strings YES or No The port type is one the strings NONE RS232 RS422 BOTH Sets the module private name to the string lt devname gt lt devname gt may include any combination of up to 20 printable characters including whitespaces NAME VE H 72 ELP Returns the current module private name Returns the type of isgdevice and its firmware version as a string in the form lt type gt XX YY Returns a list of the available commands MoCo User Manual A 4 Terminal mode When an isgdevice is accessed through a serial port primary port two possible communication modes are available that can be selected with the commands ECHO and NOECHO The differences between these two modes are described below If the primary port is not a serial port GPIB interface the device accepts the ECHO and NOECHO commands but it always responds as if it were set in the noecho mode Echo mode terminal mode This mode should be used when an isgdevice is connected to a dumb terminal In this case the user types commands on the keyboard and reads the answers and error messages on the terminal screen without computer intervention This mode is usually not active by default and the user ha
4. 2 HARDWARE DESCRIPTION 2 1 Front Panel The front panel of the MoCo unit is depicted in the following figure OUTPUT OORUN CONTROL O STOP MONITOR OUT VOLTAGE IN VOLTAGE IN MONITOR OUT f NI CURRENT IN CURRENT IN MONOCHROMATOR INBEAM OUTBEAM CONTROLLER Z gISG D D 2 1 1 INBEAM OUTBEAM There are three connectors assigned to each of the input channels INBEAM and OUTBEAM CURRENT IN Socket two lug triaxial Matches the following plug series Trompeter PL74 Keithley CS 141 Pomona 3600 and 5056 Input range from 1 25 nA to 1 mA full scale in 24 ranges Impedance virtual ground VOLTAGE IN Socket standard BNC Input range 1 25 2 5 5 and 10 V full scale Impedance 10 KQ to ground MONITOR OUT Socket standard BNC Output range 10 volts full scale corresponds to input full scale value Max current 4 mA sink or source Bandwith 80 KHz voltage input 800 Hz 1 25 nA to 10 uA full scale ranges 3 6 KHz 12 5 uA to 1 mA full scale ranges Software configuration allows selecting between current and voltage inputs inverting the polarity of the signals and selecting unipolar or bipolar modes in the internal ADC s The monitor output provides the image of the corresponding input signal at the output of the internal preamplifiers 2
5. 1 2 CONTROL OUTPUT This connector provides the output voltage to steer the optical component usually by driving a piezoelectric actuator through a high voltage amplifier or a dedicated controller Socket standard BNC Output ranges 0 to 5V 0 to 10V 5 to 5V and 10 to 10V Output impedance 50 Q Max current 25 mA sink or source MoCo User Manual 11 2 1 3 AUX1 AUX2 These standard BNC connectors are foreseen for additional hardware options that are not currently available 2 1 4 RUN STOP The RUN green and STOP red front panel LED s provide a visual indication of the state of the controller according to the following table STOP Controller state off IDLE off SCAN or SEARCH off RUN blink WAITBEAM or WAIT on PAUSED blink OVERLOAD or ALARM See the STATE request for a description of the different states of the controller 2 2 Back Panel 2 2 1 Mains socket and fuse holder The mains socket is a standard IEC CEE22 power inlet with built in fuse holder Nominal voltage 230 VAC Fuse rate 240V 160mA 12 MoCo User Manual 2 2 2 EXTERNAL CONTROL This connector provides a number of digital inputs and outputs to synchronise the operation of the controller with other devices It also provides three control bits per input channel to drive the gain control of external preamplifiers usually electrometers Socket DB15 female Inputs TTL leve
6. AD PA M2 D D DR lt empty gt R 3 DR R M2 DR MoCo User Manual AMPLITUDE AMPLITUDE Set query amplitude of oscillation Syntax AMPLITUDE lt oscAmplitude gt Description Sets the amplitude of the oscillatory component of the output signal to lt oscAmplitude gt in volts This value only has an effect in OSCILLATION mode In oscillation mode the output voltage is the sum of the value returned by the PIEZO query and an oscillatory component of fixed amplitude frequency and phase Note however that controller only generates the oscillatory component when the regulation is active or if the oscillation is explicitly started by the OSCIL command Otherwise there is no oscillatory component at the output connector Syntax 2 AMPLITUDE Answer lt oscAmplitude gt Description Returns the amplitude of the oscillatory component Examples Command AMPLITUDE 0 1 Command AMPLITUDE Answer 0 1 MoCo User Manual 23 AUTOBEAM Adjust input channel ranges Syntax AUTOBEAM Description Sets the gains of the input channels to the appropriate ranges for the current signal levels This command is only effective when the controller is in IDLE state It is intended as a simple way of readjusting the input channels when the AUTORANGE option is not set Example Command AUTOBEAM 24 MoCo User Manual AUTOPEAK 7AUTOPEAK Set query autopeak o
7. and frequency is summed to the output voltage that drives the optics Such AC component results in a oscillation of the beam intensity that can be measured by the beam monitor The controller extracts the amplitude of the intensity modulation at the oscillation frequency by applying a synchronous detection technique analogous to that used by lock in amplifiers The measured oscillation amplitude is proportional to the derivative of the beam intensity with respect to the driving voltage as it is depicted in the following figure beam oscillation amplitude set point value Average central beam intensity Output voltage In this mode the controller regulates the position of the optical element in order to keep the amplitude of the measured oscillation equal to the setpoint value If the setpoint is set to zero the most usual case the controller regulates the optical component so that it sits at the point of maximum transmitted intensity where the intensity derivative is also zero In addition to the set point value the controller requires information about the slope of the beam oscillation amplitude with respect to the driving voltage 1 1 4 Open loop When closed loop regulation is switched off the controller can be used to move the optics by driving the output voltage to fixed values In this case the voltage is not changed instantaneously but ramped at a constant programmable speed towards the desired value MoCo User Ma
8. can be selected by the SETPOINT and PEAK commands and the RIGHT or LEFT flags see SET command In position mode the operation settings can be selected by the SETPOINT and SLOPE commands With the lt sPoint gt or parameters before regulation starts the setpoint value is changed either to the given value or to the current operation point see SETPOINT command for details The new setpoint value can be checked with the SETPOINT query The other operation parameters peak or slope depending on the mode must be properly set beforehand In all cases setting of the operation parameters may be simplified by using the TUNE command Examples 36 Command GO Command GO 0 85 Command GO MoCo User Manual HELP Query list of available commands Syntax HELP Description Returns the list of available commands and queries MoCo User Manual Ae YP ae Example Command 2 HELP Answer RESET GO STOP TUNE AUTOTUNE TOTUNE AUTOPEAK OPEAK PIEZO ZO EAM AUTOBEAM SOFTBEAM SOFTBEAM OPRANGE RANGE SRANGE RANGE SET CLEAR R PAUSE E INHIBIT HIBIT TAU SETPOINT POINT MODE INBEAM AM OUTBEAM EAM GAIN ZERO OFFSET ET ADCCALIB ALIB EFAMCHECK MCHECK SPEED iD PEAK SLOPE H ISGTEST EST ECHO NOECHO 7E ADDR A CHAIN NAM
9. fuse holder 2 2 2 EXTERNAL CONTROL 2 2 3 SERIAL LINK 3 OPERATION INSTRUCTIONS 3 1 Installation and configuration 3 1 1 Serial line 3 1 2 Control output 3 1 3 Input channels 3 1 4 Inhibit and interlock options 3 2 Regulation setup 3 2 1 Regulation parameters 3 2 2 Module operation 3 2 3 Setting the oscillation mode 3 3 Usage tips 4 COMMAND SET 4 1 Command summary 4 2 Command reference MoCo User Manual ol DOWD DWDODOWDOWDAANNDA OD mk k 11 Appendix A COMMUNICATION PROTOCOL 67 A 1 Communication port 67 A 1 1 Serial line ports 67 A 1 2 GPIB interface 68 A 2 Syntax conventions 69 A 2 1 Commands and requests 69 A 2 2 Addressing serial ports 70 A 2 3 Binary data transfer 71 A 3 Common commands 72 A 4 Terminal mode 73 A 5 Binary transfer 73 A 6 Examples 74 4 MoCo User Manual 1 FUNCTIONAL DESCRIPTION The Monochromator Controller Unit MoCo is an electronic module designed to regulate the position of an optical component in a synchrotron radiation beamline typically a mirror or a monochromator by actively measuring and correcting any drift due to thermal load changes or mechanical instability The controller takes as input signals information from two beam monitors and generates an output voltage that drives the optics by means of a piezoelectric actuator or a similar device The following figure depicts the general configuration SR optics intensity or position m
10. operation point The new setpoint value can be checked with the 7SETPOINT query Syntax SETPOINT Answer lt sPoint gt Description Returns the current operation set point value Examples Command SETPOINT 0 8 Command 2 SETPOINT Answer 0 8 Command SETPOINT MoCo User Manual 57 SOFTBEAM SOFTBEAM Set query software INBEAM values Syntax SOFTBEAM lt softBeamVal gt Description When the INBEAM channel is set to software mode this command is used to set the internal INBEAM value A low pass digital filter algorithm is applied to the lt softBeamVal gt values received from the host computer The NBEAM value is set to the result of the filtering procedure Syntax SOFTBEAM Answer lt softBeamVal gt Description Returns the current software INBEAM value Examples Command SOFTBEAM 180 Command 2 SOFTBEAM Answer 180 58 MoCo User Manual SLOPE SLOPE Set query response function slope Syntax SLOPE lt slopeVal gt Description When the controller operates in position regulation mode this command sets the slope of the response function If normalisation is not active the slope must be expressed in OUTBEAM signal units per output volt If normalisation is active the slope value has also to be normalised to respect to the INBEAM value Syntax SLOPE Answer lt slopeVal gt Description Returns the slope par
11. E NAME 2V H INBEAM 7INBEAM Set query INBEAM configuration Syntax INBEAM CURR VOLT EXT NORM INV BIP UNIP lt fS gt AUTO NOAUTO INBEAM SOFT lt softThresh gt Description Sets the configuration of the INBEAM channel The signal source can be set to CURR VOLT EXT or SOFT In current CURR or voltage VOLT mode the NBEAM value is the measure of the electrical signals applied to the corresponding front panel connector When using external preamplifiers with several digitally controlled gain ranges the INBEAM channel can be set to EXT In this case the output signal of the preamplifier must be applied at the voltage input of the controller If the gain values of the preamplifier are properly set with the GAIN command the signal value will be expressed in units at the preamplifier input It is possible to select if the signal polarity is inverted INV or not NORM change the gain by specifying the full scale value lt fS gt and set or clear the autoscaling AUTO or NOAUTO The channel can also be configured in unipolar UNIP or bipolar BIP mode In bipolar mode the valid input signal range is from lt fS gt to lt fS gt In unipolar mode the range goes from 0 to lt fS gt Unipolar negative signals can be measured by inverting the signal polarity lt fS gt must be specified in units that corresp
12. ET Answer lt flag gt lt flag gt Description Returns a list of the operation flags that are currently set Examples Command Answer Command Answer Command Command Answer 56 SE NO C EA ISE R w EAMC n ET B EAMCH ECK INTERLOCK SE NO RMA HECK AUTORUN AUTORANGE INTERLOCK ISE BEAMCHECK INT ERLOCK MoCo User Manual SETPOINT SETPOINT Set query setpoint value Syntax SETPOINT lt sPoint gt Description Sets the operation setpoint value The meaning of lt sPoint gt differs depending on the operation mode In intensity mode lt sPoint gt is the relative intensity in the response function The actual operation point is obtained by multiplying lt sPoint gt by the peak height returned by PEAK For instance a value of 0 8 means that the controller will regulate the optical system to operate at 80 of the peak intensity In position mode lt sPoint gt is the absolute beam position at which the controller will make the system operate If normalisation is not set as it would be the usual case in this mode the beam position must be expressed in OUTBEAM units If normalisation is set the beam position must be also normalised by the INBEAM signal and expressed in the appropriate units With the parameter the setpoint value is changed to the current
13. INSTRUMENT SUPPORT GROUP MoCo User Manual Monochromator Controller Description The Monochromator Controller MoCo is an electronic module designed to regulate the position of an optical component in a synchrotron radiation beamline The controller corrects the position of the component typically a mirror or a monochromator by monitoring the outgoing beam and actively compensating low frequency drifts due to thermal load changes or mechanical instability Rev 2 0 May 2008 Document Versions Date Version Comments 15 02 2003 1 2a First complete version Corresponds to firmware version 01 02 04 03 2005 1 2b Minor corrections for Appendix A 31 05 2008 2 0 Firmware 2 0 includes oscillation mode and associated commands 2 MoCo User Manual Contents 1 FUNCTIONAL DESCRIPTION Operation Modes 1 Position mode 2 Intensity mode 3 Oscillation mode 4 Open loop Main Features Regulation Tuning and autoscaling Normalisation Beam detection Soft INBEAM and filtering Autorun Pause and inhibit Interlock Input signal measurement 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 Oscillation measurements and regulation 1 1 1 Pa 1 2 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 2 1 2 HARDWARE DESCRIPTION 2 1 Front Panel 2 1 1 INBEAM OUTBEAM 2 1 2 CONTROL OUTPUT 2 1 3 AUX1 AUX2 2 1 4 RUN STOP 2 2 Back Panel 2 2 1 Mains socket and
14. INV or not NORM change the gain by specifying the full scale value lt fS gt and set or clear the autoscaling AUTO or NOAUTO The channel can also be configured in unipolar UNIP or bipolar BIP mode In bipolar mode the valid input signal range is from lt fS gt to lt fS gt In unipolar mode the range goes from O to lt fS gt Unipolar negative signals can be measured by inverting the signal polarity lt fS gt must be specified in units that correspond to the signal source amps volts or units at the inputs of the external preamplifier When a full scale value is passed as parameter the internal gain is adjusted to get the closest full scale value higher than lt fS gt Syntax 0UTBEAM Answer CURR VOLT EXT NORM INV BIP UNIP lt fS gt AUTO NOAUTO Description Returns the configuration parameters of the OUTBEAM channel Examples 50 Command 2OUTBEAM Answer CURR NORM UNIP 1 25e 09 AUTO Command OUTBEAM VOLT NOAUTO Command 2OUTBEAM Answer VOLT NORM UNIP 1 25 NOAUTO MoCo User Manual PAUSE PAUSE Set clear query pause mode Syntax PAUSE ON OFF Description Switches the pause mode on or off When pause mode is switched on the controller goes into PAUSE state if the regulation was active it stops and the output voltage is kept constant When the mode is switch off the controller resumes its previ
15. OR or a human readable error message When a response message consists of more than one line the first and last lines contain a single dollar character ASCII 0x3F A 2 2 Addressing serial ports 70 The addressing features allow to dialogue with more than one isgdevice connected in a serial line daisychain configuration see A 1 If the command line does not include any addressing character the command is accepted and executed by the first device in the communication chain Binary commands and requests do not accept any addressing characters see A 5 and can only be sent to the first device in the chain Addressing does not apply in the case of GPIB communication commands and queries should not include any extra addressing characters GPIB addressing is managed according to the GPIB standard IEEE 488 1 and is not related to the addressing features described in this section Commands and requests may be preceded by any number of skip characters and or an addressing prefix The skip character is the greater than symbol gt ASCII 0x3E and can be used to address an isgdevice placed at a given physical position in the communication chain When a device founds a skip character as the first character of a command line it ignores the content of the line and forwards the remaining characters to the next device in the communication chain If a host computer connected to a chain of isgdevices sends a comman
16. R OPIOM 01 00 gt gt VER OPIOM 01 00 Sends the NOECHO command to all the devices in the chain broadcast Queries the address of the first device in the communication chain Queries the address of the third device in the chain skips the first two devices in the chain Queries the version of the device with address 12 Queries the version of the device with address LFT3 Queries the version of the third device in the chain MoCo User Manual
17. Soft INBEAM and filtering It is possible to replace the INBEAM monitor with a value that is periodically set in the controller through the serial line In what concerns the functionality of the controller this software value is equivalent to a hardware signal physically connected to the INBEAM channel This soft INBEAM signal can be used both for normalisation and for beam detection purposes Usually the soft INBEAM value is in updated in the controller at a slow rate typically once every few seconds the controller internally applies a digital low pass filter to the software values to smooth out the signal steps that even if small may perturb the regulation when normalisation is active 1 2 6 Autorun If the autorun feature is selected the controller memorises its operating state when it is switched off and resumes operation when it is switched on again see SET AUTORUN command In this way and if autorun is used in combination with the autotune feature the controller can operate unattended even in the case of an electrical shutdown 1 2 7 Pause and inhibit Under certain conditions it may be convenient to temporarily stop the controller while other instruments are operated for instance when a shutter is closed downstream or when a different optical element is realigned The controller can be forced into this pause mode either by an external inhibit input signal or through the serial line see INHIBIT and PAUSE commands O
18. ameter Examples Command SLOPE 0 0362 Command 2 SLOPE Answer 0 0362 MoCo User Manual 59 SPEED SPEED Set query scanning speed values Syntax SPEED lt scanSpeed gt lt moveSpeed gt Description Sets the speeds in volts sec applied when ramping the output voltage lt scanSpeed gt is the value used when the controller is scanning or searching the peak during a TUNE command lt moveSpeed gt is the value used when the optical instrument is moved to a in open loop by the PIEZO command During closed loop operation the previous values are ignored and the output voltage change rate is related the regulation time constant set by the TAU command Syntax SPEED Answer lt scanSpeed gt lt moveSpeed gt Description Returns the speeds in volts sec applied when ramping the output voltage Examples Command Command Answer Command Command Answer 60 SPEED 1 10 SPERED 1 10 SPEED 0 5 2 SPEED 0 5 10 MoCo User Manual SRANGE SRANGE Set query output voltage range Syntax SRANGE lt Vmin gt lt Vmax gt Description Sets the scanning range of the output voltage lt Vmin gt and lt Vmax gt are expressed in volts The controller limits the output voltage excursion to this range during scanning procedures Syntax SRANGE Answer lt Vmin gt lt Vmax gt Description R
19. and once the final voltage is reached switches to IDLE state Any regulation peak search or scanning procedure before this command is issued is aborted and not resumed Syntax PIEZO Answer lt outVoltage gt Description Returns the current value of the output voltage Examples Command PIEZO 3 45 Command PIEZO Answer 3 45 54 MoCo User Manual RESET Reset controller Syntax RESET DEFAULT Description With no parameters this command reinitialises the controller keeping the current configuration With the DEFAULT parameter it also resets the internal configuration to default values Examples Command RESET MoCo User Manual 55 SET SET Set query operation flags Syntax SET lt flag gt lt flag gt Description Sets the operation flags in the parameter list The available flags are the following Description Enables normalisation mode General flags NORMALISE BEAMCHECK UTORUN A AUTORANGE INTERLOCK Intensity mode only LEFT RIGHT Enables the beam detection feature Enables the autorun feature Enables the autorange feature Enables the interlock feature Operation point at the low voltage side of the response function Operation point at the high voltage side of the response function The command CLEAR can be used to reset the operation flags Syntax S
20. ces support binary commands or requests Binary commands and requests are are also issued as ASCII command lines but they are followed by a binary data block as described in A 5 A 2 1 Commands and requests Command lines consist of a command keyword optionally followed by parameters The number and type of parameters depend on the particular command The way a command line is terminated depends on the type of communication port see A 1 Command keywords are not case sensitive The device converts internally all the characters to uppercase before any syntax checking Parameters are also converted to uppercase unless they are enclosed between double quotes ASCII 0x22 Commands may be optionally preceded by the acknowledge character The acknowledge character is a hash symbol ASCII 0x23 that must appear in the command line immediately before the first character of the command keyword Normal non query commands never produce response messages unless the acknowledge character is used Non query command keywords always start by an alphabetical character A to Z If the acknowledge character is used the device produces the response string OK if the command execution was successful If the acknowledge character is used and the command does not executes successfully the device produces either the string ERROR or a string containing a human readable error message The behaviour depends on the current set
21. d line starting with n skip characters the n first devices in the chain will ignore the command The command line with the skip characters removed will be forwarded to the n 1 device in the chain An addressing prefix consists of an optional albhanumerical address string followed by a colon character ASCII 0x3A The address string must start by a numeric character 0 9 and consists of any combination of numbers and alphabetical A Z characters A command line with an address string will be interpreted and executed only by the first device in the communication chain whose internal address matches the one in the address string Once one of the devices recognises the address string as its own the command line will not be further forwarded to the remaining devices in the chain Leading zeros in the address string are ignored for identification purposes but can be used to access isgdevices whose internal address begins with a non numeric character MoCo User Manual An addressing prefix consisting of only the colon character with no address string is interpreted as a broadcast command In that case the command line is forwarded to all the devices in the communication chain A 2 3 Binary data transfer Commands or requests that include an asterisk symbol ASCII 0x2A as the first keyword character are followed by a binary data block The command line may include any number of ASCII formatted parameters the bi
22. e set independently and is derived from the time constant used by the beam detection algorithm see BEAMCHK command In most of the cases photodiodes and ion chambers can be directly connected to the internal electrometers of the controller In these cases the controller provides the values of the input signals in physical units amps and takes care of gain control If external electrometers with compatible gain control are used it is possible to set the controller to manage the range changes and the scale factors of the whole signal chains 1 2 10 Oscillation measurements and regulation In the special oscillation mode and when the oscillation is on see OSCIL command the measured amplitudes of the intensity oscillation can be read from the controller by the OSCBEAM request As the measurement is synchronous with the excitation the oscillation amplitude is phase dependent The oscillation can therefore be represented by two orthogonal components main and quadrature with a phase difference of 90 degrees The 20SCBEAM request returns two amplitude values that correspond to the two orthogonal components The phase reference used to evaluate the two oscillation components can be changed arbitrarily see PHASE command As the beam regulation uses only the first component main it is convenient to adjust the phase reference in such a way that the first component main is maximised and the second quadrature is null 10 MoCo User Manual
23. e the automatic range option with the SET AUTORANGE command see Usage Notes If this option is not selected and the signal value is too low or the channel saturates the proper gain can be selected either by setting the full scale value again by using the INBEAM or OUTBEAM commands or issuing the AUTOBEAM command that tells the controller to choose the most appropriate gain for the current signal level Intensity signal should be read as positive values If there are doubts about the polarity of a unipolar signal as it is often the case with intensity monitors it is preferable to set the channel in bipolar mode initially Once the sign of the signal has been identified and the channel polarity has been inverted if needed to get a positive readout the channel can then be switched to unipolar mode 3 1 4 Inhibit and interlock options The INHIBIT command can be used to enable or disable the inhibit function as well as to select the polarity of the external signal used The inhibit signal must be able to drive the TTL INHIBIT input at the back panel control connector The interlock function is also triggered by an external TTL signal applied to the corresponding input at the control connector The feature is enabled by the SET INTERLOCK command The interlock input should be driven high for normal operation When it is driven low or the cable is disconnected the controller goes into alarm mode and the output voltage is driven to MoCo User Ma
24. er when the controller operates in position or oscillation mode and in the intensity mode it is estimated from height and width of the peak 1 2 2 Tuning and autoscaling The tuning feature is a scanning procedure implemented internally in the controller aimed to measure the response function parameters required for regulation peak height and width in intensity mode or slope in position or oscillation mode Once this procedure is started it does not require any further intervention by the user If this procedure is not executed the user must explicitly set these parameters in the controller see PEAK and SLOPE commands If autoscaling is selected for any of the beam monitor inputs see INBEAM and OUTBEAM commands the gain of the corresponding channel is automatically adjusted during the tuning procedure Autoscaling only has effect during tuning the gain of the input channels being never changed when the controller is in regulation mode The autoscaling feature is different from the autorange option see SET AUTORANGE that will only be effective when the controller is not regulating idle state The tuning procedure can be started by the user see TUNE command or can be optionally triggered automatically on input channel overload conditions or after certain well defined events like the loss of the photon beam or the inhibition of the controller operation forced by a external signal see AUTOTUNE and AUTOPEAK commands By default once t
25. eturns the scaning range of the output voltage in volts Examples Command OPRANGE 10 10 Command SRANGE 2 8 Command SRANGE Answer 2 8 Command OPRANGE 0 10 Command SRANGE Answer 0 8 MoCo User Manual 61 STATE Query controller state Syntax STATE Answer Answer PAUSED lt currState gt Description Returns the current state of the controller as one of the following strings State IDLE MOVE SCAN SEARC RUN Meaning The controller is idle The output voltage is being ramped in open loop The controller is scanning the output voltage during the tuning procedure H Regulation is on but the controller is searching the operation point Regulation is on and the system is locked at the operation point WAITB WAIT EAM The controller waits for the beam is back after a beam loss The controller waits for the beam stabilisation after a beam loss OVERLOAD Any of the active input channels is saturated ALARM The interlock input has tripped the controller If the controller is in pause mode the state is preceded of the keyword PAUSED Examples Command 2STATE Answer RUN Command STOP Command 2STATE Answer IDLE 62 MoCo User Manual STOP Stop operation Syntax STOP Description Stops regulation or any scanning activity in progress and sets the unit in IDLE state When any con
26. figuration parameter is changed in the controller it always executes internally a STOP command Example Command STOP MoCo User Manual 63 TAU TAU Set query regulation time constant Syntax TAU lt regTau gt Description Sets the value of the regulation time constant in seconds Syntax TAU Answer lt regTau gt Description Returns the value of the regulation time constant Example Command TAU 1 Command TAU Answer 1 64 MoCo User Manual TUNE Start tuning sequence Syntax TUNE lt sPoint gt Description Starts the tuning procedure and at the end if tuning was successfully completed the controller goes into regulation mode Otherwise it goes into IDLE state The parameters lt sPoint gt and allow to change the setpoint before starting the tuning sequence The meaning of the parameters is the same than for the SPOINT command Example Command TUNE Command TUNE 0 8 Command TUNE TUNE PEAK Start peak tuning sequence Syntax TUNE PEAK Description In intensity mode the controller starts a tuning procedure If a peak was found and tuning is successfully completed the controller moves the optics to the peak position and goes into IDLE state Example Command TUNE PEAK MoCo User Manual 65 VER Query firmware version Syntax VER Answer MOCO XX YY Description Retu
27. ge gt Description Returns the string OK if the execution of the last command was successful or an error message describing the error in the last command Example Command Answer Command Answer Command Answer Command Answer 32 J lt zal zo n H O 2 tA Pe Ri ER Command not recognised MoCo User Manual FBEAM Query filtered input values Syntax FBEAM Answer lt inbeamFilteredValue gt lt outbeamFilteredValue gt Description Returns the values of the input channels after the digital low pass filter in the same units than non filtered values returned the 7BEAM query The filter value of the INBEAM channel is used only by the beam detection algorithm The regulation algorithm makes use of the non filtered values Both filters are set to the same time constant that can be selected with the BEAMCHECK command Example Command 2 F BEAM Answer 4 25612e 08 1 456751 MoCo User Manual 33 FREQUENCY FREQUENCY Set query oscillation frequency Syntax FREQUENCY lt oscFrequency gt Description Sets the frequency of the oscillatory component of the output signal to lt oscFrequency gt in Herzs This value only has an effect in OSCILLATION mode Only frequency values greater or equal than 500 Hz and that correspond to an oscillation period of an integer number of milliseconds can be set in the controller In
28. he programmed value The SPEED command can be used to set two velocity values that the controller applies when it drives the optics at constant speed One value is used for open loop operation and the other during scanning phases for tuning or beam search purposes The scanning range can be reduced with respect to the full operation range by means of the SRANGE command The beam detection features must be enabled or disabled as required by means of the SET CLEAR BEAMCHECK commands 3 2 2 Module operation The internal state of the controller is displayed by the front panel LED s see 2 1 4 and can be read from the controller at any time as a character string See the STATE request for a list of possible states and their meaning The PIEZO command can be used to drive the output voltage to any value within the operation range The current output value can be read at any time from the controller with the PIEZO request The controller can be put into regulation mode by means of the GO or TUNE commands GO starts regulation immediately with the current settings including the current peak or slope values In general it is preferable to use the TUNE command instead that performs a full tuning procedure as explained in 1 2 2 before switching the controller into regulation mode If the tuning procedure fails no peak is found in intensity mode for instance the controller goes into idle state and does not start regulation The STOP command inte
29. he scanning sequence is successfully completed the controller switches into regulation mode In intensity mode it is possible to make the controller to move to the peak position instead of switching into regulation mode see TUNE PEAK command In this way it is possible to position the optics automatically at to top of the transmission curve of the optics a rocking curve for instance This mode requires optics with good enough position repeatability i e a negligible hysteresis or backlash 8 MoCo User Manual 1 2 3 Normalisation The OUTBEAM monitor signal can be optionally normalised by the incoming beam intensity INBEAM This is generally needed when the controller is operated in intensity mode in synchrotron radiation beamlines to cope with the intensity decay of the source In other cases normalisation may be necessary or not depending on the particular instrumental setup and the type of beam monitor used see SET NORMALISE commana 1 2 4 Beam detection The controller may optionally analyse the incoming beam intensity INBEAM to take decisions on the presence or not of the photon beam When the beam detection feature is activated see SET BEAMCHECK command and the internal algorithm considers that the beam has been lost operation is stopped and the controller goes into wait beam mode When the beam is back the controller may wait an additional programmable time or resume operation immediately see BEAMCHECK command 1 2 5
30. hese values are only used when the controller operates in intensity mode Examples Command PEAK 1 03E3 0 17 Command 2 PEAK Answer 1 03e 03 0 17 0 52 MoCo User Manual PHASE PHASE Set query oscillation phase Syntax PHASE lt oscPhase gt Description Sets the phase of the oscillatory component of the output signal to lt oscPhase gt in degrees This value only has an effect in OSCILLATION mode In oscillation mode the output voltage is the sum of the value returned by the PIEZO query and an oscillatory component of fixed amplitude frequency and phase Note however that controller only generates the oscillatory component when the regulation is active or if the oscillation is explicitly started by the OSCIL command Otherwise there is no oscillatory component at the output connector Syntax PHASE Answer lt oscPhase gt Description Returns the phase of the oscillatory component Examples Command PHASE 90 Command PHASE Answer 90 MoCo User Manual 53 PIEZO PIEZO Set query output voltage Syntax PIEZO lt outVoltage gt Description Ramps the output voltage to lt outVoltage gt The voltage changes at the rate lt moveSpeed gt programmed with the SPEED command lt outVoltage gt is expressed in volts and must be within the range defined by the OPRANGE command The controller first goes into MOVING state while the ramp is in progress
31. ices there are two serial ports available one of each type The primary port is the one through which the isgdevice receives commands and requests There is no special configuration procedure to select the primary port After power up the device listens to all the available serial ports and the first one it receives valid data through is selected as primary If there is another one it is treated as secondary A secondary serial line port in an isgdevice can be used to connect another isgdevice In this way an arbitrary number of isgdevices can be connected in a daisychain configuration and controlled through a single serial line connection The following figure shows an example of a host computer communicating to three different devices using this feature serial line J o serial line serial line host es 4 isgdevices MoCo User Manual 67 The serial ports operate at the following settings Baudrate 9600 Parity NO Stop bits 1 In normal mode command and response messages are transferred as lines of printable ASCII characters The only exception is binary data transfer a special feature described in A 5 and only supported by a few isgdevices Commands messages sent to an isgdevice by a serial port must be formatted as sequences of printable characters terminated by a carriage return ASCII OxOD Additional control characters like line feed are ignored Response messages p
32. iven Returns the current settings hardware inhibition feature Syntax INHIBIT Answer ON OFF HIGH LOW Description Returns the current settings of the hardware inhibition feature Examples Command INHIBIT ON Command 2 INHIBIT Answer ON HIGH MoCo User Manual 41 MODE MODE Set query operation mode Syntax MODE POSITION INTENSITY OSCILLATION Description Sets the operation mode to either intensity position or oscillation The modes position and intensity must correspond to the type of beam monitor connected to OUTBEAM The mode oscillation requires an intensity monitor Syntax MODE Answer POSITION INTENSITY OSCILLATION Description Returns the current operation mode Examples Command MODE Answer POSITION Command MODE INTENSITY Command MODE Answer INTENSITY 42 MoCo User Manual NAME NAME Set query module name Syntax NAME lt appName gt Description Sets the internal module name to the ASCII string lt appName gt This name is only used for identification purposes and user convenience The maximum length is 20 characters Syntax NAME Answer lt appName gt Description Returns the application name field Examples Command Command Answer Command Command Answer MoCo User Manual NAME DEVO1 NAME DEVO1 NAME Main Monochromator
33. l compatible 47KQ to ground Outputs TTL level compatible max output current 10mA Connector layout and signals OUT Direction Signal Name GINBO OUT GINB1 OUT GINB2 Function 3 bit gain control for INBEAM external preamplifier OUT GOUTBO OUT GOUTB1 OUT GOUTB2 3 bit gain control for OUTBEAM external preamplifier OUT READY Ready output High in RUN state NREADY Not ready output Low in RUN state 6 5 4 1 2 3 7 9 8 INHIBIT Inhibit input Configurable polarity INTERLOCK Interlock input Active low Not used VCC 5 volt power supply 2 2 3 SERIAL LINK GND Logic ground This connector includes two serial line ports RS232 and RS422 Both ports have the same function and any of them can be used for communication purposes Socket DB9 female Connector layout and signals Pin Port 2 RS232 3 5 common 8 3 RS422 6 7 MoCo User Manual 13 3 OPERATION INSTRUCTIONS 3 1 Installation and configuration The installation of MoCo requires the connection of the beam monitors to the controller as well as the connection of the control output to the electronics that drives the optics A number of configurable options have also to be set through the serial line by means of software commands There is no intervention required inside the controller such as setting switches or jumpers The configu
34. n the millivolt range it would be convenient to add external amplification If the external amplifiers provide gain control that is compatible with MoCo it is advisable to setup the controller to handle the gain as it is explained in the next case Use of external amplifiers The EXTERNAL CONTROL connector at the back panel provides three TTL output bits per channel that may be used to select the gain of an external voltage or current amplifier Any combination of these bits can be used providing the possibility of setting up to eight different gain values In order to use this feature the output from the amplifiers should be connected to the corresponding VOLTAGE IN input with a BNC terminated coaxial cable External gain control must be selected with the INBEAM EXT or OUTBEAM EXT commands The GAIN command must then be used to set the actual external amplifiers gains in the configuration memory of the controller Regardless of the type of input signal used the polarity of each input channel can be inverted The associated analog to digital converted can also be set either in unipolar or bipolar mode All the input channel configuration options are selectable by means of the INBEAM and OUTBEAM commands The adequacy of the settings of an input channel can be verified by applying a known signal to the channel and reading the corresponding value with the 7BEAM of 7FBEAM requests In order to ease this procedure it may be convenient to enabl
35. nary transfer starts immediately after the end of the command line that must not include any addressing character The command is accepted and executed by the first device in the communication chain Addressing does not apply in the case of GPIB communication commands and queries should not include any extra addressing characters GPIB addressing is managed according to the GPIB standard IEEE 488 1 and is not related to the addressing features described in this section Commands and requests may be preceded by any number of skip characters and or an addressing prefix MoCo User Manual 71 A 3 Common commands The following commands are implemented in all isgdevices regardless of their specific functionality Command Description Activates the echo mode ECHO SL Must be used only in interactive mode with dumb terminals see A 4 Cancels the echo mode NOECHO Echo mode must not be active when the device is controlled by a computer program see A 4 Returns the error message corresponding to the last command or request ERR issued to the device Returns the keyword OK if no error happened during the last command Sets the module address to the string lt devaddr gt ADDR lt devaddr gt Any leading zeroes are removed from lt devaddr gt It can be formed by any combination of up to 9 alphanumerical characters 2A DDR CHAIN NAME lt devname gt Returns the current address of the device
36. nce the pause inhibit condition is removed the controller resumes operation in whatever mode was active before the pause event 1 2 8 Interlock If the interlock option is selected see SET INTERLOCK command whenever a special input is active the controller goes into alarm mode and drives the piezo output to a predefined value usually zero volts This interlock feature is intended to prevent high voltage sparkling in MoCo User Manual 9 in vaccum piezoelectric actuators when the system pressure reaches values at which electrical breakdown voltages are low 1 2 9 Input signal measurement The current values of the monitor signal can be read at any time from the controller In this way the unit can be operated as a measuring device even if the regulation function is not used Two values are available per channel a non filtered value that corresponds to the actual signal at the corresponding input and a low pass filtered value calculated by an internal digital filter see 7BEAM and FBEAM requests Every time the gain of an input channel is changed the low pass digital filter is reset to the instantaneous value If the autorange option is selected this feature may produce an apparent distortion slope discontinuity of the signal when the corresponding filtered value of the controller is used to record the shape of fast time varying signals In the current version of the controller firmware the bandwidth of the digital filter can not b
37. nt in the voltage output When the controller is not regulating the oscillation is by default switched off This command is required to start the oscillation for instance during the setup phase or for diagnostics Syntax 20SCIL Answer ON OFF Description Returns the oscillation state of the voltage output Examples Command OSCIL ON Command 20SCIL Answer ON 48 MoCo User Manual 2 0SCSAT Query saturation level Syntax 20SCSAT Answer lt satLevel gt Description In oscillation mode this query returns Examples Command 2O0SCSAT Answer 0 12 MoCo User Manual 49 OUTBEAM 0UTBEAM Set query OUTBEAM configuration Syntax OUTBEAM CURR VOLT EXT NORM INV BIP UNIP lt fS gt AUTO NOAUTO Description Sets the configuration of the OUTBEAM channel The signal source can be set to current CURR or voltage VOLT Different input connectors must be used for current or voltage signals When using external preamplifiers with several digitally controlled gain ranges the OUTBEAM channel can be set to EXT In this case the output signal of the preamplifier must be applied at the voltage input of the controller If the gain values of the preamplifier are properly set with the GAIN command the signal value will be expressed in units at the preamplifier input It is possible to select if the signal polarity is inverted
38. nterval shorter than lt inbTau gt If beam detection is active and the beam is considered lost the controller goes into WAITBEAM state and the beam intensity absolute threshold is stored When the low pass filtered INBEAM intensity stabilises at a value higher than the stored absolute threshold the controller considers that the beam is back and switches to WAIT state The controller remains in WAIT state for lt settTime gt seconds before resuming normal operation The beam detection feature can be activated and cancelled by the SET and CLEAR commands The lt inbTau gt parameter sets also the time constant of the internal digital filters that produce the filtered values returned by the 7FBEAM query Syntax BEAMCHECK Answer lt absThresh gt lt relThresh gt lt inbTau gt lt settTime gt Description Returns the parameters set by the BEAMCHECK command Examples Command BEAMCHECK 0 0 3 Command 2 BEAMCHECK Answer 0 0 333333 1 024 0 28 MoCo User Manual CHAIN Query secondary serial port status Syntax 2CHAIN Answer YES NO RS232 RS422 NONE Description Returns whether or not YES or NO there is another instrument connected to the secondary serial port as well as its electrical specification RS232 or RS422 The secondary serial port is the port that is not used for communications with the host computer and that can be eve
39. ntually used for daisy chaining of modules Example Command 2CHAIN Answer NO RS422 MoCo User Manual 29 CLEAR CLEAR Clear operation flags Syntax CLEAR lt flag gt lt flag gt Description Clears any combination of the operation flags See the SET command for a list of available flags and their meaning Syntax CLEAR Answer lt flag gt lt flag gt Description Returns a list of the operation flags that are currently NOT set Examples Command Answer Command Command Answer 30 SE RIGHT B CL 2G RIGHT B EAMCH EAR A ET UTORANGE NORMA EAMCHE ECK NORMAL ISE E AUTORANGE MoCo User Manual ECHO Switches the echo mode on Syntax ECHO Description This mode is intended to be used when the instrument is connected to a dumb character terminal In this mode the characters received by the unit through the serial lined are sent back to the terminal and error messages are produced as soon as the corresponding errors are detected If the instrument is controlled by a program running in host computer the echo mode should be switched off see NOECHO command In this case the error messages can be requested by means of the ERR query Example Command ECHO MoCo User Manual 31 ERR Query last error Syntax ERR Answer OK lt errorMessa
40. nual 17 a safe value The safe voltage value is usually zero volts but it can be set to any other value within the operation voltage range by means of the OPRANGE command 3 2 Regulation setup 3 2 1 Regulation parameters In order to be able to access the regulation features first the operation mode has to be selected with the MODE command The selected mode either position or intensity must correspond to the type of OUTBEAM monitor The signal normalisation option must also be enabled or disabled as required by means of the SET CLEAR NORMALISE commands The regulation time constant has also to be set with the TAU command and the operating point with the SETPOINT command When operating in intensity mode the controller needs also to know the height of the peak response function of the optics This value can be entered explicitly in the controller with the PEAK command but in general it is simpler and more convenient to let the controller measure the peak height by itself during a tuning procedure as explained in 1 2 2 The same is applicable for the slope of the response function However even if not recommended in general it is possible to explicitly enter a slope value in the controller In the case of intensity regulation the slope of the response function is indirectly estimated from the peak width set through the PEAK command In position mode the SLOPE command can be used for this purpose paying attention to the sign of t
41. nual 7 1 2 Main Features 1 2 1 Regulation The monochromator controller implements regulation based on a simple integral correction algorithm There are no proportional or differential parts as in full featured PID controllers Therefore the regulation settings are reduced to a single time constant value tau It is possible to program the controller with time constant as low as 1 millisecond but in order to achieve proper regulation tau must be set longer than the response time of the whole optical system including the driving actuator the mechanics and the outgoing beam monitor Most of the piezoelectric drives used in synchrotron radiation instrumentation have response times that are between 5 and 100 milliseconds Therefore even in the case of very light mechanics low inertia and fast enough beam monitors the time constant of the controller should not be set lower than 100 milliseconds to 1 second A controller that uses only integral part guaranties the stability of the closed loop avoids risks of induced oscillations and is well adapted to correct slow drifts due to thermal effects However it cannot compensate for faster externally generated vibrations or oscillations that a full PID controller might damp In order to accept tau values in time units see TAU commana the controller requires the low frequency gain of the whole optical system This is obtained from the slope of the response function Such slope is a required paramet
42. olts or amps respectively If the channel is set to EXT the value is expressed in the corresponding units at the input of the external preamplifier If the INBEAM channel is set to SOFT mode lt inbeamValue gt is expressed in whatever unit were used in the SOFTBEAM command Example Command 2 BEAM Answer 4 256e 09 1 033e 07 MoCo User Manual 27 BEAMCHECK BEAMCHECK Set query beam detection parameters Syntax BEAMCHECK lt absThresh gt lt relThresh gt lt inbTau gt lt settTime gt Description Sets the parameters of the internal beam detection algorithm The relative threshold lt relThresh gt is the value used to detect the beam is lost and beam is back conditions The time constant lt inbTau gt determines the time scale applied in seconds When controller starts operation an absolute beam detection threshold is set to predefined values If the INBEAM input channel is set in current or voltage mode the threshold is set to 2 of the full scale range In software mode the threshold is set to the lt softThresh gt parameter see INBEAM command Once regulation is active the absolute threshold is continuously recalculated by multiplying the low pass filtered INBEAM intensity by the relative threshold value lt relThresh gt For instance if the relative threshold is 0 2 the beam is considered lost when the INBEAM intensity drops below 20 of its current value in a time i
43. ond to the signal source amps volts or units at the inputs of the external preamplifier When a full scale value is passed as parameter the internal gain is adjusted to get the closest full scale value higher than lt fS gt When the INBEAM vale is used for normalisation see SET NORMALISE the channel cannot be set in bipolar mode In software mode SOFT the INBEAM value is set by the host computer by issuing the SOFTBEAM command The parameter lt softThresh gt is the initial detection threshold used for beam detection purposes when regulation starts It must be expressed in the same units than lt softBeamVal gt in the SOFTBEAM command Syntax INBEAM Answer CURR VOLT EXT NORM INV BIP UNIP lt fS gt AUTO NOAUTO or SOFT lt softThreshold gt Description Returns the configuration parameters of the NBEAM channel 38 MoCo User Manual Examples Command Answer Command Command Answer Command Command Answer MoCo User Manual INBEAM CUR INBI B INBEAM R R NORM UNIP 1 25e 09 AUTO EAM INV 9e 8 R INV UNIP 1e 07 AUTO EAM SOFT INBEAM SOFT 1 39 INFO Query module configuration Syntax INFO ALL Description Returns a multiline answer with the current configuration The information is presented as a list of valid commands with the appropriate parameters that can be sent back to the controller in
44. onitor intensity monitor O O aoa S Incoming beam LJ A DRIVER Monochromator Controller INBEAM OUTPUT OUTBEAM The first monitor INBEAM measures the intensity of the radiation beam coming into the optical element and it is used for normalisation and to detect the presence of the beam The second monitor OUTBEAM measures either the intensity or the position of the beam after the optics The type of monitor that is required for a particular application depends on the response of the optical system The regulation algorithm drives the optical element usually by tilting a crystal or mirror in order to cancel the difference between the measured value POSITION or INTENSITY and a user predefined setpoint value When using an intensity monitor the previous scheme does not allow to regulate the beam at the maximum of intensity for instance at the top of the reflectivity curve of a crystal monochromator To overcome this limitation the controller may be also configured in an third regulation scheme OSCILLATION that adds a small oscillatory component to the optics drive and applies synchronous detection techniques to measure the derivative of the system response Among the features of the controller there are the following Low current or voltage inputs with built in gain control Regulation time constant from 1 ms to 1 minute Detection of beam presence A
45. or requests Noecho mode host computer This is the default In this mode no characters are echoed and no error messages are returned unless they are explicitly requested by means of the 7ERR request This mode is intended to be used when a program running in a host computer communicates with the controller sending commands and analysing the answers Commands are keywords starting by an alphabetical A to Z character followed by optional parameters Commands do not produce any answer from the controller Requests are keywords starting by a question mark character The controller returns an answer to every request it receives even in the case of errors An answer consists on one or more lines terminated by a carriage return line feed character sequence ASCII 0x0D 0x0A When the answer consists of more that one line the first and last lines contain a single character plus the two line terminator characters always present If wrong or not valid request is sent to the controller its answer is the ERROR keyword MoCo User Manual 15 A more detailed description of the protocol including some advanced communication features not mentioned here like command acknowledgement daisy chaining of controllers or addressing is presented in the Appendix A 3 1 2 Control output The output voltage range has to be set to match the input range of the electronics used to steer the optical instrument usually a d
46. oscillation mode the output voltage is the sum of the value returned by the PIEZO query and an oscillatory component of fixed amplitude frequency and phase Note however that controller only generates the oscillatory component when the regulation is active or if the oscillation is explicitly started by the OSCIL command Otherwise there is no oscillatory component at the output connector Syntax FREQUENCY Answer lt oscFrequency gt Description Returns the frequency of the oscillatory component Examples Command FREQUENCY 160 Command 2 FREQUENCY Answer 166 6 34 MoCo User Manual GAIN GAIN Set query preamplifier gain table Syntax GAIN INBEAM OUTBEAM lt g0 gt lt g1 gt lt g2 gt lt g7 gt GAIN INBEAM OUTBEAM DEFAULT Description Sets in the controller the gain values of the preamplifier of an input channel INBEAM or OUTBEAM This command is primarily intended to load the available gain ranges in the controller memory when external preamplifiers with compatible gain control are used In this case the input channel has to be set to EXT mode MoCo outputs three control bits per channel to drive the preamplifier gain Bit patterns from O binary 000 to 7 binary 111 may be used to select the up to 8 different amplification ranges The values gO to g7 are the gain values of the corresponding ranges The gain values for non valid bit pa
47. ous mode of operation A similar effect can be obtained by a change of polarity of a external logic signal see INHIBIT commana Syntax PAUSE Answer ON OFF Description Returns the current state of the pause mode Examples Command PAUSE Command PAUSE Answer ON Command PAUSE OFF Command PAUSE Answer OFF MoCo User Manual 51 PEAK PEAK Set query peak parameters Syntax PEAK lt pkHeight gt lt pkWidth gt lt pkPos gt Description Sets the peak height and width parameters that the controller uses when operates in intensity mode lt pkHeight gt is the peak value of the response function of the system If normalisation is not set the peak height must be expressed in OUTBEAM units If normalisation is set the peak height must be also normalised by the JNBEAM signal and expressed in the appropriate units lt pkWidth gt is the full width at half maximum FWHM of the peak expressed in volts at the output signal lt pkPos gt is the peak position expressed in volts This value is not actually used by the controller but it is stored for information purposes In general instead of using the PEAK command it is recommended to use the TUNE command to let the controller to estimate these values Syntax PEAK Answer lt pkHeight gt lt pkWidth gt lt pkPos gt Description Returns the settings for peak height and width as well as the peak position T
48. peration range of the output voltage expressed in volts The output signal is always limited to the range between lt Vmin gt and lt Vmax gt that should always between 10V and 10V The lt Vsafe gt is usually zero and corresponds to the voltage that the controller will output in case it goes into ALARM state after an interlock event Syntax OPRANGE Answer lt Vmin gt lt Vmax gt lt Vsafe gt Description Returns the operation range and the safe output voltage in volts Examples Command OPRANGE 5 5 Command OPRANGE Answer 5 5 0 46 MoCo User Manual 0SCBEAM Query main and quadrature signal amplitudes Syntax 20SCBEAM Answer lt mainSignal gt lt quadSignal gt Description In oscillation mode returns the amplitudes of the OUTBEAM signal at the frequency of the oscillatory component As the detection is synchronous this query returns two values one value lt mainSlgnal gt that corresponds to the component in phase with the oscillation and another one lt quadSignal gt that corresponds to the component in quadrature at 90 degress of phase shift Examples Command 20SCBEAM Answer 1 345 0 03625 Command OSCIL OFF Command 20SCBEAM Answer 0 0 MoCo User Manual 47 OSCIL 0SCIL Start query oscillation state Syntax OSCIL ON OFF Description In oscillation mode this command starts stops the oscillatory compone
49. ptions Syntax AUTOPEAK lt flag gt lt flag gt AUTOPEAK OFF Description Enables the autopeak modes selected by the list of flags entered as parameters The parameter OFF clears all the autopeak flags Every autopeak mode has an associated trigger condition If a particular mode is enabled and the trigger condition happens when the controller not regulating a TUNE PEAK command will automatically be executed internally as soon as the trigger condition is removed The available flags and conditions are the same than for the AUTOTUNE command Syntax AUTOPEAK Answer lt flag gt lt flag gt or OFF Description Returns a list with the autupeak flags currently set If no autopeak flag is set it returns the string OFF Examples Command AUTOPEAK OFF Command 2 AUTOPEAK Answer OFF Command AUTOPEAK BEAMLOSS Command AUTOPEAK INHIBIT Command AUTOPEAK Answer BEAMLOSS INHIBIT Command AUTOPEAK OFF OVERLOAD Command 2 AUTOPEAK Answer OVERLOAD MoCo User Manual 25 AUTOTUNE AUTOTUNE Set query autotuning options Syntax AUTOTUNE lt flag gt lt flag gt AUTOTUNE OFF Description Enables the autotuning modes selected by the list of flags entered as parameters The parameter OFF disables all autotuning modes Every autotuning mode has an associated trigger condition If a mode is enabled and the t
50. ration parameters are stored in an internal non volatile memory and are retained after power off on cycles 3 1 1 Serial line Access to the internal functions of the controller and configuration parameters can only be achieved through the serial line Therefore the first step required is to connect the controller to a host computer or to an ASCII character terminal Any of the two available serial ports RS232 or RS422 can be used for this purpose the controller will respond by the same port it receives the commands The settings of both serial ports are 9600 baud No parity 1 stop bit All the commands and requests sent to the controller are sequences of printable ASCII characters terminated by a carriage return ASCII OxOD character The answer of the controller depends on the communication mode selected that can be changed with the commands ECHO and NOECHO Echo mode terminal mode This mode should be used when the controller is connected to a dumb terminal In this case the user types commands on the keyboard and reads the answers and error messages on the terminal screen without computer intervention This mode is not active by default and the user has to send the ECHO command every time the controller is powered on In echo mode all the characters sent to the controller are echoed back to the terminal The controller also sends human readable messages to be printed on the terminal screen whenever an error is detected in commands
51. re fixed and do not change during regulation Phase adjustment is tricky Possibility of saturation OSCSAT 3 3 Usage tips The INFO request provides a summary of the configuration parameters in the controller It is a convenient and fast way of checking the current configuration In general it is only advisable to select the autorange mode SET AUTORANGE when the controller is used only as a measurement instrument to monitor the beam When it is used for regulation it is normally better to switch auitorange off CLEAR AUTORANGE If in intensity mode a TUNE command does not succeed the controller remains in IDLE state instead of going into regulation mode and switching to RUN state Among the possible causes for this behaviour are the following there is no beam the peak is not centered and not completely contained in the scanning range or there is a shift in the beam intensity due to a radiation background in the monitor The default parameters for the beam detection feature BEAMCHECK 0 should work properly in nearly all practical cases It is not advisable to change the default values unless the rather cumbersome algorithm and the influence of the different parameters are well understood MoCo User Manual 19 4 COMMAND SET 4 1 Command summary
52. rigger condition happens when the controller is in regulation mode a TUNE command will automatically be executed internally as soon as the trigger condition is removed The available flags and conditions are the following Flags Trigger condition BEAMLOSS The photon beam is back after a beam loss and the controller leaves a waiting state Beam detection see SET BEAMCHECK must be enabled OVERLOAD An overload in any of the active input channels was detected INHIBIT The controller was inhibited by an external control signal The inhibit feature see INHIBIT command must be enabled Syntax AUTOTUNE OFF Answer lt flag gt lt flag gt or OFF Description Returns a list with the autuning flags currently set If no autotuning flag is set it returns the string OFF With the parameter OFF returns the list of autuning flags that are not currently set Examples Command AUTOTUNE OFF BEAMLOSS INHIBIT Command 2 AUTOTUNE Answer BEAMLOSS INHIBIT Command AUTOTUNE OFF Command 2AUTOTUNE Answer OFF 26 MoCo User Manual BEAM Query input values Syntax BEAM Answer lt inbeamValue gt lt outbeamValue gt Description Returns the current values of the input channels in the units that correspond to the particular settings of each channel If a channel is set to VOLT or CURR mode the channel value is expressed in v
53. river for piezoelectric actuators The operation range is selected by setting the min and max voltage values by means of the OPRANGE command The min and max voltage values must be comprised between 10 and 10 volts The current range can be read back from the controller with the OPRANGE request The operation of the voltage output can be tested by forcing the output to several voltage values within its operation range with the PIEZO command and verifying the output signal with an external meter 3 1 3 Input channels The input channels INBEAM and OUTBEAM must be connected to the corresponding beam monitors In most of the cases where the beam detection is based on photodiodes ion chambers or other devices that provide a low current signal the monitors can be directly connected to the triaxial current inputs of the controller If a beam monitor generates a voltage signal or if an external preamplifier is used the monitor signal should be connected to the voltage input of the corresponding channel The only exceptions to the previous paragraph are those cases in which the INBEAM channel is either not used no normalisation no beam presence detection required or it is replaced by a software value In the first case the configuration of the INBEAM channel is not required In the second case the controller must be set to expect software values instead of a hardware signal see INBEAM SOFT and SOFTBEAM commands In cases where physical moni
54. rns the version number XX YY of the firmware Example Command VER Command MOCO 01 02 66 MoCo User Manual Appendix A COMMUNICATION PROTOCOL This section covers the communication protocol implemented in a number of instruments developed in the Instrument Support Group at the ESRF An instrument that adheres to this protocol and conventions is referred as an isgdevice The information is presented here in a generic way and most of the information applies to any isgdevice Some of the options like GPIB communication or binary data transfer may not be implemented in a particular instrument and therefore the related information should be ignored A 1 Communication port An isgdevice is equipped with one or more communication ports A communication port may be an asynchronous serial line or a GPIB interface The type and number of ports as well as the electrical interface RS232 or RS422 depend on the particular instrument In a general case an isgdevice is equipped with a RS232 port a RS422 port and a GPIB interface If an isgdevice is equipped with both serial ports and GPIB the GPIB interface only becomes active if no cables are connected to the serial line ports Whenever a connection is made to any of the serial ports the GPIB interface is disabled A 1 1 Serial line ports Serial line ports are asynchronous communication ports electrically compatible with either the RS232 or RS422 specification In most of the isgdev
55. roduced by the device consist on lines terminated by a carriage return line feed character sequence ASCII 0x0D Ox0A A 1 2 GPIB interface Some isgdevices include a communication interface compliant with the GPIB IEEE 488 1 standard Every isgdevice with this type of interface has a default GPIB address The procedure for changing the address as well as the default value depends on the type of device Command messages sent to the device must be always terminated by an EOI bus signal or a terminator character Both characters carriage return ASCII 0x0D and line feed ASCII 0x0A may be used as message terminators Response messages produced by the device when it is addressed as talker consist on lines terminated by a carriage return line feed character sequence ASCII 0x0D Ox0A as in the case of serial lines The EOI bus signal is activated with the last character of every message line As well as serial lines and in addition to the normal ASCII based commands GPIB communication provides some support for binary data transfer This only applies to special cases as described in A 5 68 MoCo User Manual A 2 Syntax conventions In the most usual case remote control is implemented by an application program running in a host computer that sends commands and requests to the isgdevice as sequences of ASCII characters The syntax rules are described below See A 6 for practical examples Some devi
56. rrupts regulation and switches the controller to idle state The output remains stable at the voltage value present at the output connector when the command was received 18 MoCo User Manual When the controller is in regulation mode and receives a PIEZO or any other command intended to set one of the internal parameters it first stops regulation and afterwards executes the received command Therefore every time a controller parameter is changed regulation must be explicitly restarted with a GO or TUNE command The TUNE PEAK is a special version of the TUNE command only valid in intensity mode that works somewhat differently than explained above once the tuning procedure is successfully completed the controller drives the output voltage to the value at which the peak maximum was found and then switches to idle state Normally the controller starts a tuning procedure when it is explicitly requested by means of the TUNE or TUNE PEAK commands The AUTOTUNE and AUTOPEAK commands may be used to instruct the controller to automatically start tuning sequences after certain events 3 2 3 Setting the oscillation mode Setting up the oscillation mode requires in addition to the basic configuration the selection of the parameters of the oscillation excitation These parameters are the frequency amplitude and phase of the oscillatory component that is summed to the controller output see FREQUENCY AMPLITUDE and PHASE commands This parameters a
57. ry oscillation state 48 STATE Query controller state 62 BEAM Query input values 27 FBEAM Query filtered input values 33 SOFTBEAM SOFTBEAM Set query software INBEAM values 58 OSCBEAM Query main and quadrature signal amplitudes 47 OSCSAT Query 49 RESET Reset controller 55 ECHO Select echo mode 31 NOECHO Cancel echo mode 44 ERR Query last error 32 ADDR ADDR Set query serial line address 22 CHAIN Query secondary serial port status 29 NAME NAME Set query module name 43 VER Query firmware version 66 HELP Query list of available commands 37 MoCo User Manual 4 2 Command reference ADDR ADDR Set query serial line address Syntax ADDR lt slAddress gt Description Sets the serial line address to the lt slAddress gt The address may be any alphanumerical character string The maximum length is 9 characters Any leading zeroes in the address are discarded When different modules are daisy chained for communication a particular module can be accessed by preceding any command with a prefix formed by the module address followed by acolon character If the first character of the address is non numeric a leading zero must be added Syntax 2 ADDR Answer lt slAddress gt Description Returns the serial line address of the module Examples Command Answer Command Command Answer Command Command Answer 22 2A AD 2A
58. s to send the ECHO command every time the device is powered on In echo mode all the characters sent to the device are echoed back to the terminal The device also sends human readable messages to be printed on the terminal screen whenever an error is detected in commands or requests Case conversion takes place before the characters are sent back to the terminal therefore characters are echoed back as uppercase even if they are typed and sent to the device as lowercase The backspace character ASCII 0x08 has the effect of deleting the last character received by the device In this way a minimum editing functionality is provided Noecho mode host computer This is usually the default In this mode no characters are echoed and no error messages are returned unless they are explicitly requested by means of the ERR request This mode is intended to be used when a program running in a host computer communicates with the controller sending commands and analysing the answers A 5 Binary transfer Binary transfer is a special mode that extends the standard protocol allowing faster data transfer Most of the isdevices do not implement binary transfer and therefore this section is not relevant to them to be developed MoCo User Manual 73 A 6 Examples In the following examples it is assumed that the device is in noecho mode Commands and requests Command 1 Answer Command 2 Answer Command 3 An
59. swer Command 4 Answer Errors Command 5 Answer Command 6 Answer Command 7 Answer Command 8 Answer Command 9 Answer Command 10 Answer NAME ERROR NOECHO 10 answer 2VER MOCO 01 02 NAME My Device 10 answer NAME My Device OK ERR OK 2 VER ERROR 2ERR N0 answer Wrong Number of Parameter s Sets the device in noecho mode Queries the type and version number of the device Sets the private name of the device There is no response message If the acknowledge character is used the device produces an OK response message If no error happened during the last command or request Errors in requests extra white space in this case always produce a response message If an error happened returns the corresponding error message Errors in commands missing parameter in this case do not produce response messages If the acknowledge character is used the device produces a response message If an error happened returns the corresponding error message Addressing assumes daisychaining of at least three isgdevices 74 Command 11 Answer Command 12 Answer Command 13 Answer Command 14 Answer Command 15 Answer Command 16 Answer NOECHO NO answer ADDR 12 gt gt ADDR LFT3 12 VER MOCO 01 02 OLFT3 VE
60. the case that reconfiguration is needed With the parameter ALL returns additional calibration parameters that should not normally modified by the average user Example Command 2 INFO Answer MOCO 01 02 Current settings NAME no name ADDR OPRANGE 0 10 0 INBEAM SOFT 1 GAIN INBEAM DEFAULT OUTBEAM EXT NORM UNIP 1 25e 08 AUTO GAIN OUTBEAM 0 1e 06 0 1e 07 1e 08 0 0 O zZ O iS NTENSITY 1 0 TPOINT 0 8 U 1 RIGHT BEAMCHECK NORMALISE EAR AUTORUN AUTORANGE INTERLOCK TOTUNE OFF UTOPEAK OFF EAMCHECK 0 0 333333 1 024 0 RANGE 0 10 ED 2 50 HIBIT OFF LOW D A eH fo gt Fl el T E ae HHNNWPYPPANHN Y G Z 40 MoCo User Manual INHIBIT INHIBIT Se query hardware inhibition settings Syntax INHIBIT ON OFF HIGH LOW Description Enables or disables the hardware inhibition feature ON or OFF and selects the active level of the inhibit signal HIGH or LOW When this feature is enabled and the external logic signal inhibit switches to its active level the controller goes into PAUSE state and regulation stops When the inhibit signal switches to its non active logic level regulation resumes The controller behaviour is analogous to the obtained with the PAUSE command but in this case it is hardware dr
61. ting of the echo mode see A 4 Binary commands are special cases where the command keyword includes an extra asterisk symbol ASCII 0x2A immediately before the first alphabetical character Binary commands may include any number of ASCII formatted parameters but the command line must be followed by a binary data block as described in A 5 Requests are query commands that produce response messages from the device Requests keywords always start by a question mark character ASCII 0x3F If the request is successful the content of the response message depends on the particular request If request fails the device produces either the string ERROR or a string containing and human readable error message The behaviour depends on the current setting of the echo mode see A 4 The acknowledge character has no effect when used with requests MoCo User Manual 69 Binary requests are a special case where the request keyword includes an extra asterisk symbol ASCII 0x2A immediately after the question mark character In binary requests instead of an ASCII response message the device sends to the host a binary data block as described in A 5 Response messages consist of one or more ASCII character lines The way every line in a response message is terminated depends on the type of communication port see A 1 A response message may contain either the output of a request an acknowledgement keyword OK or ERR
62. tional to the intensity of the beam The controller expects a dependency of the signal with the output voltage that presents a maximum at a certain position of the optics as it is represented in the figure Such a peak shaped response function is usually produced by a double crystal monochromator or by a mirror followed by a fixed slit Beam intensity operation point set point value Output voltage 6 MoCo User Manual In this mode the controller regulates the position of the optical element in order to keep constant the operation at a relative position of the peak value Intensity normalisation by the INBEAM signal is usually required to cope with the intensity decay found in a synchrotron radiation beamline For a certain setpoint value the operation point can be selected either at the left or at the right side or the peak For proper operation in this mode in addition to the relative set point value the controller needs the absolute height of the peak and the peak width As in the position mode these additional information can be either provided externally or obtained by the controller itself by means of a tuning procedure see Tuning below 1 1 3 Oscillation mode This mode implements a special regulation scheme to be used with intensity monitors The intensity mode described above does not allow to regulate the beam at the maximum of beam intensity In the special oscillation mode a small AC component of fixed amplitude
63. tors are required each input signal should fall in one of the following three categories Current signals The current input has to be selected with the INBEAM CURR or OUTBEAM CURR commands and the signal must be connected to the corresponding CURRENT IN input with a compatible triaxial plug It is preferable to use a triaxial cable to carry the signal from the monitor to the controller If the monitor is floating what in general is the best case the current source a floating photodiode for instance should be connected between the inner conductor and the inner shield of the cable the external shield being connected to the mechanical ground and used for overall shielding If the monitor is grounded the current source should be connected to the inner conductor and the external cable shield used for signal return In this case is still advisable to use triaxial cable and leave the inner shield unconnected at the monitor side The inner shield will be still effective as signal guard to reduce low frequency current injection 50 Hz in the signal path along the cable 16 MoCo User Manual Voltage signals The voltage input has to be selected with the INBEAM VOLT or OUTBEAM VOLT commands and the signal must be connected to the corresponding VOLTAGE IN input with a BNC terminated coaxial cable The full scale value of the voltage inputs can be internally selected to 4 ranges from 1 25 volts to 10 volts Therefore if the monitor signal were i
64. tterns have to be set to zero All the gain values have to be expressed in volts per input unit It is convenient to set the input unit as the physical unit of the signal at the preamplifier input usually volts or amps This command can also be used when the input channel is in CURR mode but the gain of the built in electrometers has been changed with respect to the default values by modifying internal components In that case the DEFAULT parameter can be used to restore the default gain values This command cannot be issued when the input channel is in VOLT mode Syntax GAIN INBEAM OUTBEAM Answer lt g0 gt lt g1 gt lt g2 gt lt g3 gt lt g4 gt lt g5 gt lt g6 gt lt g7 gt or DEFAULT Description Returns the gain table of the specified input channel This command cannot be issued when the input channel is in VOLT mode Examples Command GAIN OUTBEAM 0 1e6 0 le7 1e8 Command 2GAIN OUTBEAM Answer O 1le 06 0 1le 07 1e 08 0 0 0 MoCo User Manual 35 GO Start regulation Syntax GO lt sPoint gt Description Puts the unit into regulation mode The controller drives the actuator in order to stabilise either the intensity or the position of the beam depending on the current mode selected see MODE command With no parameters the operation point is defined by the current values of the operation settings In intensity mode the operation settings
65. utomatic tuning and autoscaling Full control by serial line Software INBEAM monitor Hardware handshake with other devices Gain control of external preamplifiers MoCo User Manual 5 1 1 Operation Modes As mentioned above the controller has to be operated in different close loop modes depending on the type information provided by the OUTBEAM monitor and the regulation scheme When the regulation is not active the controller can be used to drive the optics in open loop from a host computer 1 1 1 Position mode In this mode the OUTBEAM signal is proportional to the position of the beam The controller then assumes a dependency of the signal with the output voltage that varies monotonically at least around the central range as it is represented in the figure This is the signal shape expected from a beam position monitor after a mirror or monochromator Beam position signal 4s operation point PPSA Output voltage r4 set point value In this mode the controller regulates the position of the optical element in order to keep the beam position constant For proper operation in this mode in addition to the set point value the controller requires information about the slope of the response function This value can be either provided externally or estimated by the controller itself by means of a scanning procedure see Tuning below 1 1 2 Intensity mode In this case the OUTBEAM signal is propor

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