RMD681 - Nokeval
Contents
1. Sensor Fault some channel has improper connection overranging or a broken sensor or wires AD Error A D converter is not working Needs service SETTINGS General submenu General submenu has settings that do not belong to the other groups Scan Automatic changing of the displayed channel e Off The channel is changed only manually using buttons AY e All All the active channels are scanned at one second interval e Alarming Like All but if any channel has active alarm only alarming channels are scanned e Mux The channel to be displayed is selected using digital inputs K1 K4 like the analog output If the Output Source setting is set to Mux the Output Addr must correspond to the digital input at K5 K8 otherwise dashes are shown in the channel display and the reading display is empty The scanning can be always stopped temporarily by pushing 4 or Y in the normal state Then the channels can be selected manually using 4V buttons and alarm levels viewed using button Automatic scanning is activated again if the buttons are not touched for 10 seconds or 4 and Vv are pushed together CfCode Selecting password for the settings If enabled the configuration menu can not be entered anymore without knowing the password How to enter the password using the front panel see chapter User interface Input submenu Input submenu contains the input settings It is further divided in Common and2. Accuracy Load mA Range Accuracy Load Ohm Ranges Common A D conversion Speed Cable length Overvolt category 0 02 C C 0 05 rdg 1 C lin error 55 and 100 mV 0 1 rdg 0 01 mV gt 1 Mohm 1V 1 1 V 2 5V 1 2 5 V 10V 10 10 V 0 05 rdg 0 01 V gt 1 Mohm 20 mA 0 008 mA 50 80 ohm 0 400 ohm 0 4000 ohm 0 40000 ohm 16 bits 32767 Cycle time is number of channels 1 12 seconds All channels in 1 4 seconds Max 30 m EMC Not rated input common mode potential may not exceed 50 VDC or 120 VAC with respect to ground Analog output mA output Range Accuracy Load V output Range Accuracy Common Source Channel select time Digital inputs Use Direction Passive level Active level Load Cable length 0 20 mA or less 0 008 mA 0 600 ohm 0 10 V or less 0 005 V Certain channel externally selected channel minimum maximum or serial comms lt 40 ms Selecting the input channel to be displayed or for the analog output can be read with serial comms PNP active high internal pull downs 0 5 1 V 3 30 V about 5 kohm Max 3 m EMC Serial connection Connection Protocols Baud rates Bits Max response time Reading all chs Min response time Termination Alarms Response Relays Device unpowered RS 485 Nokeval SCL Modbus RTU 1200 2400 4800 9600 19200 38400 57600 SCL 8N1 M
3. 0 41 noos me eLoaT Sme 14 15 noor m8 eLoaT Sme 16 17 noos mm FLOAT Sime 28 29 1014 CJ2 FLOAT Signed 1015 Digi inputs BYTE Unsigned 0 255 31 32 1016 Out FLOAT 1017 Rel BYTE Bits 0 3 34 35 1018 Cycle time FLOAT The channel 1 8 readings can also be read as 16 bit signed integers in registers 1000 1018 The readings have as many digits after the decimal points as is set with the Dec setting in the settings of that channel E g Dec 1 divide the integer by 10 10 to get the reading Holding registers The registers 0 1999 contain the configuration settings Register pair 2000 2001 is the Ext register that can be used to control the analog output The input readings can be accessed through Holding registers 5000 onwards although using Input registers is recommended Register Name Tye Vaus 0 __ ConfiGeneraliScan enm Seetabe ET 1 fConhGenerahctcods eos 3_ ConfinputiCommon Differential Boo a ConfinputiCommonPulup Boo 8 9 ConfinputChtiLopass ELoaT Unsigned The register address of the other 26 172 channels is obtained by adding 21 Ch 1 to the channel 1 settings 185 Conama Cmnieves Boo oo o 17 188 189 Conf Alarms Lev2 FLOAT Signed aa conas woo SSS a fconaamsnc2 woo ooo o Ce T Discrete input registers The discrete input registers 0 7 correspond to the digital inputs K1 K8 Enum tables Table E1 Scan 18 Modbus 1 Tab
4. 13 and 14 cold junction temperatures The response consists of characters 0123456789 The scientific notation 1E3 is not used In case of invalid reading the response consists of dashes With over underflow the response is 4444 or uuuuu The reading is always represented with six significant digits except negative readings with five e g pi would be represented 3 14159 After power up before the first reading is obtained the transmitter will return NAK 0 message to MEA commands in order to prevent logger software from logging invalid readings 15 MEA SCAN 1 8 Returns the readings on channels 1 8 separated by one space See MEA CH for data representation OUT CH 1 23 45 Writes to the Ext channel a value of 23 45 The analog output can be set to follow the Ext channel by selecting Out Source Ext DICH 1 Returns the state of the digital input 1 connector K1 The answer is either 0 or 1 without the quotation marks DI SCAN 1 8 Returns the states of the digital inputs separated with a space e g 1100111 1 The digital input K1 is returned first MN xxxxx Commands used by Mekuwin configuration software MODBUS PROTOCOL Supported commands e 2 Read Discrete Inputs reading the digital inputs e 3 Read Holding Registers reading the settings e 4 Read Input Registers reading the input readings e 6 Write Single Register changing t
5. Ch1 Ch8 submenus Input Common submenu Speed Mesurement speed selection Speed 1 is intended for normal use and the specifications are valid for that The higher speeds will increase noise 12 General Alm1 Alm2 Output Alarms Serial Differential Internal grounding of the differential inputs Not applicable to resistance inputs like Pt100 e No The transmitter uses a semiconductor switch to groud the negative terminal of the channel being measured e Yes The inputs are differential or floating and the potential equalisation must be done externally Pullup Sensor wire break sensing If enabled a weak current is fed to thermocouple sensors to detect breaks Input Ch1 Ch8 submenus Sensor Input range and sensor selection Off Channel not used It is recommended to set unused channels off in order to speed up the measurement cycle e 55mV 100mV 1V 2 5V and 10V Voltage inputs Can measure also negative voltage however 2 5V range reaches only 1 V The reading is in millivolts or volts according to the name of the range e 20mA and 50mA Current inputs Can measure also negative current The jumper inside the case has to be closed e 400ohm 40000hm and 400000hm Resistance inputs The resistor is connected in three wire connection The reading in ohms e Pt Ni Cu and KTY83 Resistance thermometers RTD s The nominal resist
6. User manual 10 3 2008 V1 4 RMD681 8 channel transmitter Nokeval DESCRIPTION RMD6871 is an 8 channel measurement unit for temperature sensors and other electrical inputs The unit has both analog and serial outputs The analog output can be selected among the input channels using binary PNP inputs Every channel has two alarm levels controlling two common alarm relays The inputs are galvanically isolated from the outputs and the supply voltage but not from each other There is a 2 5 digit display and four push buttons that can be used to monitor the readings and to change the settings The settings can also be edited from a personal computer using RS 485 serial connection Protocols offered are Nokeval SCL and Modbus RTU SPECIFICATIONS Inputs Pt100 Range Accuracy Thermal drift Sensor current Ni100 Range Accuracy Cu10 Range Accuracy KTY83 Range 200 700 C 0 05 rdg 0 25 C 0 02 C C 0 25 mA multiplexed 60 180 C 0 05 rdg 0 25 C 200 260 C 1 C 55 175 C PtXXX NiXXX CuXXX Range Thermocouples Same as Pt100 Ni100 range lin error 400 1700 C 0 3 C 0 2300 C 0 5 0 2300 C 1 100 900 C 0 2 1000 2300 C 2 160 950 C 1 150 1370 C 0 5 150 900 C 0 5 0 1300 C 0 1 0 1700 C 0 5 0 1700 C 0 5 200 400 C 1 OAs SG CO Ambient comp Accuracy mV Ranges Accuracy Load V Ranges
7. aced with a minus sign Monitoring state Monitoring can be used to examine some internal readings Use the monitor mode in the PC software or the built in monitor mode The built in monitoring is started by pressing and Y together Select the item using AY keys and exit with Items In1 In8 latest readings Min Max minimum and maximum reading on channels 1 8 Avg average of the channels Ext ext channel controlled by serial communications see Out Source Isens measured resistance sensor measurement current normally about 0 25 mA 11 To set a password push 4 to select Set means password will be used then push gt to enter the new password Cod 0 is shown The password is a sequence of six keypresses using all the four keys Enter the same password twice if they match Set is shown again and you can exit with If they didn t match Off is shown Redo from start To disable a password push Y to select Off and exit with CJ1 C2 internal cold junction temperatures Digi inputs digital inputs as an integer 0 255 Out analog output value mA or V Rel alarm relays 0 none 1 Rel1 2 Rel2 3 both active Cycle time measurement cycle time in seconds Last item is Diag that can be used to see diagnostic messages Push gt If nothing happens then there is no messages If happens try AY to see if there is several messages Exit with RMD681 has two messages
8. ance is set in RO see below The reading is in celsius e TcB TcT Thermocouples The result is in celsius RO The nominal resistance of a resistive temperature sensor With Pt and Ni sensors this is the resistance at 0 C e g Pt100 RO 100 With Cu and KTY83 the nominal resistance is given at 25 C If the real resistance of the sensor at the nominal temperature is known it can be fed here in order to cancel the sensor error Lopass First order lowpass filter for the reading Will attenuate noise and disturbances Set time constant to 63 of step change in seconds or 0 to disable Dec The number of digits after the decimal point to be displayed Can be set negative to round the corresponding number of last digits to zero In addition this defines the decimal point location to the Modbus 16 bit integer readings input regs 1000 1015 Examples how 123 45678 is rounded Dec 2 123 45 Dec 0 123 Dec 2 100 Pts Number of scaling points The scaling means converting the reading to represent some other engineering reading The scaled value is used on the display serial output analog output and alarms e 0 No scaling e 1 One point offset correction The reading corresponding to Mea is scaled to be Sca1 when displayed using appropriate offset value e 2 Two point scaling Readings from Mea to Mea2 are scaled to be Sca1 to Sca2 on the display Any values can be used these have
9. etected Configuration state Common alarms Channel pRel1 gy Rel2 Serial Fault Conf Channel alarms N ok eva I RMD series Normal state After the power up a channel number and a when a serial message is received at correct reading is displayed Depending on the Scan address Fault indicator is lit when a sensor is setting a fixed channel is diplayed or the channels broken or there is internal fault Conf is lit when in are scanned The channel can be selected configuration state These indicators are not manually using AY buttons and after the last dependent on the channel selected channel minimum and maximum readings and the average are displayed A1 and A2 indicate whether there is active alarms at the selected channel They blink when an alarm Rel1 and Rel2 indicators show the real state of the level is shown in operator menu M is not used alarms active or not active Serial indicator is lit Operator menu The alarm levels can be changed without entering If common alarm level is used among the channels the configuration state Use gt button to select the Alarms Cmn levels the channel display will function Alarm level 1 Alarm level 2 Normal show Co Common when an alarm level is state Blinking A1 or A2 indicates that an alarm displayed level is displayed In this state the level can be changed by pressing first A or V and then AVP If an automatic display scan mode is used When do
10. g This is because the lowpass filter could work against the delay functions a short but large input disturbance would Serial connection Serial command is received then it is processed and finally a response is sent To process a commend and to form a response takes typically 3 maximum 15 ms on SCL protocol except MEA SCAN can take up to 65 ms The whole process for MEA SCAN 1 8 takes abt 120 ms 9600 baud and 70 ms 38400 baud Conf menu gt Edit value gt ic Edit value Submenu Item 3 2 every transmitter connector K5 Bringing a voltage to this terminal activates the output Edit value make the lowpass filter to give wrong decaying reading for a long time causing a false alarm The alarm information from each channel is combined using OR logic meaning that the common alarm will be considered active if the alarm is active on any channel Before applying to the relay the activation and deactivation delays are added and the polarity reversed if NC operation is enabled The Rel item in Monitor menu shows the real relay state 1 pulling Modbus protocol is faster since there is no need to format the readings to be human readable So the response time is typically 5 ms maximum 15 ms Reading all the inputs using Read Input Registers takes abt 70 ms 9600 baud and 20 ms 38400 baud USER INTERFACE Front panel Serial communication Internal or external fault d
11. hannel 1 8 that is used to control the analog output Addr Multiplexing address Visible only when Source Mux Select address 0 15 The analog output is active only when the digital inputs K5 K8 are controlled to correspond to this address Range Analog output range mA or V Rdg1 Out1 Rdg2 and Out2 Output scaling Reading Rdg1 on display corresponds to output signal Out1 in mA or V and Rdg2 to Out2 These have not to be the end points since the transmitter is able to extrapolate Alarms submenu Common settings of the alarms Cmn levels No Every channel has alarm limits of its own e g Input Ch1 Alm1 Level Yes Common alarm levels are used on all channels The levels are defined in this menu items Lev1 and Lev2 However the alarms has to be switched on on every channel separately Lev1 Lev2 Common alarm levels when Cmn levels is enabled ActDelay DeaDelay Alarm activation and deactivation delays An alarm must be continuously active for the time specified in ActDelay in order to cause a real common alarm The functional diagram in chapter Operation clarifies this The delay times are given in seconds The maximum delay time is 3495 seconds Note that the alarm is taken from unfiltered reading so these delays are the only protection against false alarms NC1 NC2 Inverting the relay operation Affects only the coils of the relays but not the LED indicators e No Normal operation
12. he settings and the Ext channel e 16 Write Multiple registers changing the settings e 17 Report Slave ID checking the device type e 109 Meku Mekuwin configuration software uses this When the settings are changed by writing to a Holding register the settings are changed to the Data types WORD 16 bit setting CODE Password 12 bits O not used non voltatile EEPROM memory immediately It might take several dozens of milliseconds for the transmitter to respond to the next command The maximum length of the command is 150 bytes The maximum length of the response is the same This sets the limit to number of registers with commands 3 4 and 16 The command 17 will return 0x11 lt byte count gt 0x00 OxFF followed with RMD681 V1 3 A123456 for example When the serial connection settings are changed the changes do not affect until the transmitter is powered down This is to prevent breaking the connection while making the changes BOOL Off on setting Only the least significant bit is used BYTE One byte setting Only the lower word of the Modbus register is used ENUM Option list setting The options listed in section Enum tables FLOAT 32 bit floating point number IEEE 754 Least significant word first LSWF little endian Within one Modbus register the data is represented the most significant byte first MSBF big endian Input registers Register fegiter tame Type Vas 8 9 ho 5 oat Sge
13. is several sensors connected to the same conducting target the potential equalisation can be done with one wire connecting the target to terminal 3 or 6 at any channel Digital inputs Digital PNP inputs are used to select the input channel for the analog output or the channel that is displayed Analog output Either mA or V output can be used They can t be used at the same time they do work but the other is very inaccurate The analog output ground is the same as the power supply ground Serial connection Serial connection RS 485 is available at connector B Its ground is connected to the supply and analog output grounds If the potential between serial devices is not equalized through the power network it is recommended to connect their Common terminals together with an auxiliary wire If this potential equalisation is not possible then it is advisable to engage the RS 485 floating jumper inside the case see Jumpers D1 is the more positive terminal Nokeval A or The maximum recommended distance is 1 km The cable should be a twisted pair wire gauge 0 5 mm minimum Alarm relays The device is equipped with two relays capable to switch 250 VAC If either of the relays is connected to a line voltage the other must not be connected to low voltage circuits Relay 1 contacts are closed when no power is applied to the transmitter Power supply Supply voltage 24 VDC is connected in connector L 100 86 J
14. ive state First four terminals K1 K4 are used to select the input channel that is used for the analog output When these are passive 0 V channel 1 is used K1 is the least significant bit If 8 channels is not enough several RMD681 s can be connected in parallel to one mA output In this case only one transmitter is activated at a time using the other digital inputs K5 K8 When the binary word 0 15 at these terminals correspods to the Addr setting in Output menu the analog output is activated There is two ways to use this If the terminals K1 K8 are connected in parallel in several transmitters and a different address is selected in every transmitter Output Addr any transmitter can be activated using a binary word Maximum number of transmitters is 16 16 input channels 16 input channels RMD680 DI RMD680 DI DI OUT DI OUT Single analog Transmitter Channel output 4 20 mA select select The other way is to select address 1 in every transmitter and connect a enable line to Alarms Every channel has two alarms and they can be either low or high level alarms Alarms 1 operates relay 1 and alarm 2 relay 2 If any channel has an alarm active the corresponding relay will activate These channel alarms simply judge whether the reading is above or below the alarm level The A1 and A2 indicators on the display indicate the states on the channel being viewed The alarms are taken from unfiltered readin
15. le E5 Table E8 Protocol 0 SCL Table E6 Table E7 19
16. ne push General Scan it has to be interrupted temporarily Just push 4 or Y 10 Configuration state Press and 4 simultaneously two seconds to enter the configuration state When entered the Conf led will light If configuration password is set you will need to enter it Cod 0 displayed In case the password is not known switch the power off hold and gt keys pressed and switch the power on again PWDC is displayed briefly This will also set the serial settings to their default values The main level of the configuration menu is shown You can select among menu items using AY keys To edit the setting push gt to start editing and to get back to the menu How to edit see section Editing The menu is organizated hierarchically You can enter General Input Output Alarms and Serial submenus by selecting them with AY keys and entering the submenu with gt key See the menu chart in chapter Settings When all settings are done exit from the menu with key Two options are shown Save to keep the settings made and Undo to discard all changes Select Save or Undo and push P Editing Most data types are edited with simply AY keys finally exiting with key Floating point values such as scaling and the lopass filter are edited with AV keys select digit to edit blinking with and change it with AY When the decimal point is blinking it can be moved with A Y The first digit can be repl
17. normally open the relay pulls when an alarm is active e Yes Inverse operation normally closed the relay releases when an alarm is active 14 Serial submenu Serial connection settings Note that the changes here do not affect until the configuration state is exit Protocol Serial protocol e SCL Nokeval SCL protocol The description of this protocol can be obtained from Nokeval www pages and the commands are listed in chapter SCL protocol e Modbus Modbus RTU protocol The registers and data representation are described in chapter Modbus protocol Address Serial bus address Valid choices for SCL are 0 123 and for Modbus 1 247 Baud Baud rate selection Options 1200 2400 4800 9600 19200 38400 and 57600 bits per second Bits Parity and stop bits Visible with Modbus only SCL uses always 8N1 Options 8E1 recommended 801 8N2 SCL PROTOCOL A more detailed description of the Nokeval SCL protocol can be downloaded from Nokeval www pages http Awww nokeval com under the data acquisition pages RMD681 understands the following SCL commands TYPE Returns the model name and software version RMD681 V1 4 without the quotation marks SN Returns the serial number e g A123456 MEA CH 1 Returns the scaled reading on channel 1 Channels 1 8 can be read this way Moreover e channels 9 and 10 minimum ja maximum e channels 11 and 12 average and Ext e channels
18. not to be the end points Mea1 Sca1 Mea2 and Sca2 Scaling points Visibility of these settings depend on the Pts setting Unscaled reading Mea is converted to Sca1 and Meaz2 to Scaz2 Alm1 and Alm2 Submenus for alarm settings on each channel Input Ch1 Alm submenus Every input channel has two alarm functions They are configured in submenus Alm1 and Alm2 below each input channel settings Some more settings concerning the alarms are in the Alarms submenu in the Conf main level Type Alarm type Off Alarm not used e Lo Low level alarm The alarm is activated when the scaled reading on this channel goes below the alarm level e Hi High level alarm 13 Level Alarm level If the Cmn Levels setting in Alarms submenu is on these channel specific level settings are hidden and replaced with one common setting in Alarms submenu There is no hysteresis function in the alarms It is replaced with user selectable delays see Alarms menu Output submenu Analog output settings Source Where the output is taken from e Mux Multiplexing selecting the channel using the digital PNP inputs Single Fixed channel see Ch below e Min Minimun reading among input channels 1 8 e Max Maximum reading e Avg Average reading Ext Ext channel controlled by serial communications SCL OUT or Modbus Holding 2000 Ch Fixed input channel selection Visible only when Source Single Select input c
19. odbus 8E1 801 8N2 SCL typ 3 max 65 ms Modbus typ 5 max 15 ms after changing settings 300 ms for the next command SCL 110 ms 38400 baud Modbus typ 28 max 38 ms 3 5 characters Jumper selectable None or 110 ohm 1 nF Same as meas cycle definable delay 2 A 250 VAC Relay 1 closed 2 open Supply voltage Voltage 24 V 415 Current lt 100 mA Environment Oper temperature Pollution class Other Weight Mounting Connectors Galvanic isolation Regulations 10 60 C 1 350 g 35 mm DIN rail 1 5 mm detachable Inputs together Power supply and analog and serial output together These groups isolated from each other EMC immunity EN 61326 Annex A EM field Burst Surge Conducted RF 61000 4 3 10 V m criterion A 61000 4 4 any port 2 kV criterion B 61000 4 5 power supply 1 kV line to line criterion A 61000 4 5 inputs not applied short distance wires 61000 4 5 serial and outputs 1 kV line to ground criterion B 61000 4 6 any port 3 V criterion A shielded cable used EMC emissions EN 61326 RF emissions CISPR 16 class B INSTALLING Connections Input channels Conn C 1 2 Conn D 3 4 Conn E 5 6 Conn F 7 8 Isb Channel select K Device select msb Supply L voltage Input channels There is three terminals for each input channel positive and negative input and the ground The ground connections are connected together am
20. ong the channels but the positive and negative inputs are differential and can tolerate about 1 V above or below the ground Potential equalisation is needed to keep the input voltages near the ground Most simple way to guarantee this is to connect the negative input to ground 2 3 and 5 6 This is not applied to resistance measurements that use all the three terminals Voltage inputs The voltage inputs mV or V are connected in terminals 1 and 2 or 4 and 5 In addition to that the terminals 2 3 and 5 6 are recommended to be linked together in order to equalise the potential The current input jumper must be open Current inputs The current input mA is connected in terminals 1 and 2 or 4 and 5 In addition to that the terminals 2 3 and 5 6 are recommended to be linked together in order to equalise the potential The RS 485 ig Analog out Alarm relay 2 Alarm relay 1 current input jumper must be closed inside the case near the connector Resistance inputs Pt100 and others The negative end of the sensor is connected with two wires in terminals 2 and 3 The positive end is connected in terminal 1 with one wire The sensors must be isolated Thermocouple inputs The thermocouples are connected in terminals 1 and 2 or 4 and 5 as in the figure If the sensors are electrically isolated from the target the sensor potential is recommended to be bound by linking terminals 2 3 or 5 6 Instead if there
21. res every active channel at a time When all is done the transmitter does one internal measurement that means measuring the RTD sensor current or one of the four cold junction sensors There is only one A D converter and it is connected to one channel at a time using semi conductor switches along with the RTD current generators The A D input is differential measuring only the difference between the positive and negative input terminal However these voltages must be within 1 V of the input circuit ground which is available at OR function among ch s gt Delay amp NO NC Rel Reidy output logic the terminals 3 and 6 at every input channel With resistance sensors the third wire will do it but with the other inputs the potential equalisation should be done as described in chapter Connections If the wires are short it may not be necessary See also Differential in chapter Settings The normal measurement speed is 12 channels per second If there is 10 channels used they are updated every second Remember that there is one internal measurement in addition to the external measurements Analog output and digital inputs RMD681 has one analog output It can be selected to follow a selected input channel or use the digital input to select the channel to be output See Output Source setting For external channel selection the device is equipped with 8 digital inputs of PNP type A positive voltage 3 24 V is act
22. umpers Inside the case there is one jumper next to each input channel connector It has to be closed when using mA input and else open In the middle card there is a jumper marked 2 wire It should be closed when there is no potential equalisation between the RS 485 devices E g Nokeval 711 serial converter has no common terminal so this jumper should be used Next to that there is an AC termination jumper J6 that Settings The settings can be done with either the front panel buttons or the serial connection Using the buttons is described in chapter User interface and the settings in chapter Settings The PC software needed is called Mekuwin It is free from Nokeval web site To use it you need should be enabled in the first and last device on the RS 485 bus When neither of these functios is desired the jumper may be parked between the top pins of J5 and J6 To access the jumpers prise a screwdriver between the bottom and top covers near the locking tabs at the case ends also a RS 485 connection to your computer An inexpensive alternative is Nokeval DCS770 USB to RS485 converter Select the same communication parameters in each end before attempting to connect See also chapter Settings OPERATION Digital inputs A D converter Sensor processing Serial interface Analog output Scaling Lowpass filter Display Ke E 4 123 4 Comparator Other channels Measurement The transmitter measu
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