User manual
Contents
1. Speed Byte time Byte time Byte time Byte time 9 bits 10 bits 11 bits 12 bits 2400 bps 3 750 ms 4 167 ms 4 583 ms 5 000 ms 4800 bps 1 875 ms 2 083 ms 2 292 ms 2 500 ms 9600 bps 0 938 ms 1 042 ms 1 146 ms 1 250 ms 19200 bps 0 469 ms 0 521 ms 0 573 ms 0 625 ms 38400 bps 0 234 ms 0 260 ms 0 286 ms 0 313 ms 57600 bps 0 156 ms 0 174 ms 0 191 ms 0 208 ms 115200 bps 0 078 ms 0 087 ms 0 095 ms 0 104 ms Page 5 SIAM Conversor Version 2 0 User manual software i automatismes morvedre CONFI GURATI ON SWI TCHES The eight configuration switches placed if one side of the converter case are inactive OFF in upper position and active ON in the lower position as indicated by the arrow The default setting for the configuration switches is shown in the picture on the right S1 S2 S3 S8 inactive and S4 S5 S6 S7 active af 5 SO 12 3 456 708 D IP ONI The purpose of each one of the configuration switches from left to right is described in the following table Switch Function Description S1 Pull up Activates the 390 Q pull up resistor to stabilize the bus Must be set in only one node in the RS 485 network S2 Pull down Activates the 390 Q pull down resistor to stabilize the bus Must be set in only one node in the RS 485 network s3 End of bus Activates the 220 Q end of bus resistor to avoid reflections in the bus Must be turned on in the end nodes of the bus and turned off in a2. MONI TORI NG LEDS SIAM Conversor Version 2 0 User manual 1 LEDs for rate converter according to the following table baud rate 2 monitoring These LEDS indicate the comms baud detected by L1 L2 L3 Detected baud rate Off Off Off Off On Off On Off Off 2400 bps 4800 bps On On Off 9600 bps Off On Off Off On On 19200 bps 38400 bps Off On On 57600 bps 2 RS 485 bus On On On 115200 bps LED for reception state Turns on when data is received from the RS 485 bus 3 LED for transmission state Turns on when the device is transmitting data to the 4 LED for external power supply Indicates if an external power supply is present If the converter is getting power only from the serial port it will work but no LED will be active unless jumper J1 is active as described in the previous page because normally a serial port can t source enough current to keep all the LEDs active at the same time Page 9 software i automatismes morvedre SIAM Conversor Version 2 0 User manual In some custom models of the converter the RS 485 bus RS 232 port connector DB9 female connector where a normal serial extender cable can be connected RS 485 bus connector Connect here the RS 485 bus cable to the 485 and485 terminals and the cable shield to the Shield terminal Connecti
3. Page 7 software i automatismes morvedre SIAM Conversor Version 2 0 User manual Configuration jumpers are not accesible from outside the converter because their functionality is not required for most applications If it were necessary to set these jumpers the converter s plastic case should be open by removing the four screws in the bottom side They re placed just beside the configuration switches as shown in the picture on the left Its purpose is described in the following table Jumper Function Description Ji LED activation without external power supply If this jumper is activated closed the converter will turn on the LEDs even when no external power supply is present This is not advisable because the current consumption with all LEDs active can be higher than the current supplied by typical PC serial ports and this can cause malfunction and converter resets J2 RTS CTS loopback Connects the lines RTS and CTS in the RS 232 port J3 DTR DSR loopback Connects the lines DTR and DSR in the RS 232 port J4 DTR RI loopback Connects the lines DTR and RI in the RS 232 port Loopback connections RTS CTS and DTR DSR RI can be necessary if the software that controls the serial port requires hardware flow control Otherwise it s recommended to leave the jumpers inactive open to minimize current consumption Page 8 software i automatismes morvedre
4. SIAM Conversor Version 2 0 EXTERNAL RS232 RS485 _ AUTO SPEED s AUTO RTS CONVERTER User manual SIAM Conversor Version 2 0 User manual software i automatismes morvedre CHARACTERI STI CS External RS232 RS485 microcontroller based converter with automatic transmission detection Auto RTS and automatic speed detection Auto Speed Works at 7 different speeds 2400 4800 9600 19200 38400 57600 y 115200 bps with byte sizes of 9 10 11 and 12 bits Three selectable working modes automatic transmission and reception only transmission only reception Echo option switch Fully compatible with Siemens PC PPI Cable for connection with Siemens S7 200 PLCs End of bus resistances to avoid reflexions and pull up and pull down to stabilize the RS 485 bus Up to 64 converters in the RS 485 bus without repeaters Switches for configuration of byte size and pull up pull down and end of bus resistances Internal jumpers for configuration of loopback connections for hardware flow control LED indication for external power supply reception state transmission state and working speed Port powered operation with connector for external 7 30VDC power supply optional DB9F connection for RS 232 port DB9M DB9F 1 8m serial cable optional Pluggable 3 way terminal block connector for RS 485 port Other connectors available under special request DB9M DB9F RJ 45 RJ 11 RJ 12 RCA jack etc Optional
5. morvedre Software i Automatismes Morvedre S L L Vent de Ponent 22 46520 Puerto de Sagunto Valencia Spain www siam es info siam es
6. DB9 shields is optional though recommended to increase noise immunity Connection to serial ports with DB25M is also possible using standard DB25 DB9 adapters SI EMENS S7 200 PLC CONNECTI ON This converter can replace Siemens communication adapter PC PPI Cable for S7 200 CPUs Moreover no external power supply is required in this case because the CPU supplies 24VDC through its PPI port The connection is described in the following diagram DB9H CPU S7 DBSH Conversor Shield For short distance connection to an S7 200 it s recommended to use an specific version of the converter with a DB9 male connector which allows direct connection to the PLC and powering the converter with only a standard serial port extender cable Page 11 SIAM Conversor Version 2 0 User manual software i automatismes morvedre STANDARD RS 485 DEVI CE CONNECTI ON Standard RS 485 devices with DB9 connectors tipically assign 485 and 485 signals to pins 8 and 3 So the connection diagram is just like the one in the previous page for the Siemens S7 200 removing the power supply and ground signals pins 7 and 2 Specific versions of the converter can be requested with any kind of connectors ready to connect to any RS 485 device by specifying the type of connector to use and the correspondence between the RS 485 and power signals and the pins in the connector Page 12 SIAM Conversor Version 2 0 User manual so
7. DIN rail mounting clip Dimensions 100 x 50 x 25 mm CONTENTS 232 485 converter User manual 220 VAC to 12 VDC transformer optional DB9M DB9F 1 8m serial cable for RS 232 PC port connection optional DIN rail mounting adapter optional Page 2 SIAM Conversor Version 2 0 User manual software i automatismes morvedre INTRODUCTION SiAM Conversor is a RS 232 to RS 485 communications converter with automatic detection of transmisi n direction Auto RTS and automatic detection of the communications baud rate Auto Speed In the following figure you can see the layout of the configuration switches display LEDs and connectors in the converter case DB9 female connector for RS 232 Power supply connector RS 485 bus connector Configuration switches LED for external power supply LEDs for communication monitoring LEDs for baud rate monitoring Page 3 SIAM Conversor Version 2 0 User manual software i automatismes morvedre THE RS 485 BUS AND TRANSMI SSION CONTROL The RS 485 bus conventional term for the TIA EIA 485 norm offers several advantages over the RS 232 e It allows multipoint communications up to 32 nodes while RS 232 only allows point to point communications between 2 stations e The communication distance can be increased to more than 1000 metres depending on the transmission speed e Transmission speed can be much higher than i
8. ftware i automatismes morvedre FREQUENTLY ASKED QUESTI ONS The converter is not receiving anything and the reception LED is always on Check that the 485 and 485 cables have been correctly connected and have not been swapped Check also end of bus pull up and pull down configuration switches End of bus resistance must be turned on in the first and the last device in the RS 485 bus Pull up and pull down resistances must be turned on in only one device in the bus The converter is not functioning properly when powered only from the serial port The converter gets its power from the RTS and DTR lines in the RS 232 port The software that s controlling the port must activate these two lines so the converter can work without external power If the software is not activating these lines or can t be configured to do so then the converter will need an external power supply Even in the case where RTS and DTR lines are active there can still be problems PC serial ports can source a very limited amount current In some cases like in notebook PCs the current is so low that the converter can t work at all In normal serial ports the converter should work fine but care must be taken to reduce its consumption as much as possible The converter automatically detects the absence of an external power source and turns off all the LEDs unless jumper J1 is active but if this is not enough the following actions are recommended e Disab
9. ion speed accurately it s very important because transmission deactivation delay is calculated depending on this speed In this mode the converter calculates the actual transmission speed measuring pulse widths in the RS 232 port The detected speed will be shown in the speed monitoring leds Speed detection is performed dinamically so that if the transmitting device changes the communication speed the converter will detect it after a short time and will automatically adjust transmission deactivation delay The converter has a security mechanism in automatic speed detection mode that automatically resets the converter and sets the detected speed to its lowest value 2400 bps after a 5 second approx interval with no activity in the transmission line Whenever posible it s convenient to program the RS 232 devices so that they wait for at least one byte time before beginning the transmission in order to ensure that the device which transmitted previously has released the bus before the new transmission begins If this is not taken into account communication errors can occur At higher speeds RTS delay after transmission is lower than the device s processing time and so this problem is less important In fact this converter has been used to communicate with many kinds of RS 485 devices with no related to delays The following table shows the minimum delay times for every speed with 9 10 11 and 12 bit sized bytes
10. le pull up and pull down resistors in the converter Those resistors if necessary can be activated in any other node in the bus e Disable the end of bus resistor Normally it s not necessary unless the baud rate is 38400 bps or higher e Disable loopback connections for hardware flow control Page 13 software i automatismes morvedre SIAM Conversor Version 2 0 User manual ELECTRIC CHARACTERI STI CS Parameter Units Minumum Maximum Supply voltage V 7 30 Supply current mA 10 150 Power consumption W 0 07 4 5 Operating temperature C 0 50 Operating humidity 10 90 COMMUNI CATI ON CHARACTERI STI CS Parameter Units Minimum Maximum Number of stations in the RS 485 bus 64 Communication speed bps 2400 115200 1 Baud rate of 115200 bps is in the limit of the conversor performance and may present some error rate which can be overcome by retries by the protocol in the data link layer Page 14 SIAM Conversor Version 2 0 User manual software i automatismes morvedre COPYRI GHT This product with all its components and this manual are property of Software i Automatismes Morvedre S L L Total or partial reproduction of design program electronic board or manual is forbidden Any action against this statement will be prosecuted according to intellectual property laws June 2004 Page 15 software i automatismes
11. ll the intermediate nodes S4 Echo disable If S4 is OFF echo in the RS 485 bus is enabled This means that all the data transmitted by the converter will also be received by itself If S4 is ON nothing will be received when transmitting The echo option can be necessary for some particular software but normally this switch should be turned on S5 TX enable This switch enables transmission to the RS 485 bus If turned OFF no data will be sent to the bus and the device would only be able to receive data if S6 is ON It should normally be active S6 RX enable This switch enables reception from the RS 485 bus If turned OFF no data will be received from the bus and the device would only be able to transmit data if S5 is ON It should normally be active Page 6 software i automatismes morvedre SIAM Conversor Version 2 0 User manual Switch Function Description 57 58 Byte size These two switches select one between the four possible byte sizes including data start stop and parity bits according to the following table S8 S7 Bytesize Possible configurations Data bits Parity Yes No Stop bits OFF OFF 9 bits 7 No 1 OFF ON 10 bits 8 No 1 7 Si 1 7 No 2 ON OFF 11 bits 8 Yes 1 8 No 2 ON ON 12 bits 8 Yes 2 If communications byte size is unknown try all possibilities to see which one works best
12. n RS 232 up to 10 Mbits s e Higher noise immunity The physical layer consists in a twisted pair shielded or unshielded whose wires are named 485 485 although they are also named TX TX or A B A 1 bit is translated in a positive differential voltage between 485 and 485 higher than 0 2V tipically 1 5V and while at same time a 0 bit establishes a negative differential voltage between 485 and 485 The RS 485 bus is a a f duplex shared medium where stations cannot transmit and receive data at the same time The bus nodes must enable their transmission drivers only when they have data to transmit and disable them immediately after transmission to release the bus and allow the rest of nodes to transmit The signal that controls the transmission enabling is the Request to Send or RTS signal The control of this signal in the RS 232 ports in a PC or any other device with an RS 232 port is complicated because the serial port must be low level programmed to ensure a short delay in disabling RTS after transmission SiAM Conversor incorporates an automatic microcontroller based RTS control that guarantees the correct data transmission from the RS 232 side to the RS 485 side without the need of programming the RTS control line in the RS 232 port Page 4 SIAM Conversor Version 2 0 User manual software i automatismes morvedre AUTO RTS AND AUTO SPEED WORKI NG MODE In Auto RTS mode knowing the actual transmiss
13. ng shield will reduce noise in the RS 485 bus External power supply connector Connect here the external power supply between 7 and 30 VDC The positive terminal is in the center pin connector can be of another type like DB9 male DB9 female RJ 45 RJ 11 RJ 12 etc In these cases the connection between lines 485 485 and Shie d to the pins in the connector will be specified for each particular case In those models the standard connector for external power supply can be removed because power can be supplied through some of the unused pins in the bus connector It s possible to change the standard 3 way pluggable terminal block connector for the RS 485 bus by a 5 way connector which allows the connection of the external power supply through the two additional poles In this case the connection diagram would be as shown in the picture on the right Don t power the converter through the RS 485 bus connector in the models where it can be done and through the standard external power supply connector at the same time Only one power supply connection can be used Page 10 SIAM Conversor Version 2 0 User manual software i automatismes morvedre PC CONNECTION Connection between the converter and the RS 232 PC port is performed by a normal serial port extending cable as the following diagram shows DB9H DB9M 485 Conversor Lili PC Shield Connecting
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