RS-485 wiring information
FAQ #100152
There are confusing screw terminal identifier terminologies around. Depending on the manufacturer the identifiers used are in conflict to the identifiers you can find in SBC manuals.
General
RS-485 is a Bus-system, therefore the signal wires shall not be crossed.
| Converter | PCD |
| Rx-Tx (or D) | Rx-Tx |
| /Rx-/Tx/ (or /D) | /Rx-/Tx |
Sometimes "+Data" and "-Data" can be found on devices. Then "+Data" propably has to be connected to "/Rx-/Tx" (or /D) and "-Data" to "Rx-Tx" (or D).
Converters
Some products form other manufacturers (p.e. RS232 - RS485 converters) are often inversly indicated. Therefore it is sometimes necessary to cross the wires.
| Converter | PCD |
| Rx-Tx | /Rx-/Tx/ |
| /Rx-/Tx/ | Rx-Tx |
Profibus and Profi-S-I/O
| Profibus | Colour | PCD7.T160 | D-Sub 9pin on PCD | Port 2 on PCD3.M3 and M6 |
| A=RxD /TxD-N | green | D | pin 8 | D |
| B=RxD /TxD-P | red | D/ | pin 3 | /D |
Example for the port 3 of the PCD3.M5540 as Serial-S-Bus
RS485 connection (Serial-S-Bus) between PCD3.M5540 port 3 (S-Net D-Sub used as RS485 Serial-S-Bus) and PCD2.M5540 port 2 (connector block X3):
| PCD3.M5540 (D-Sub "S-Net", port 3) | PCD2.M5540, X3, port2 equipped with a PCD7.F110 |
| pin 3 | terminal 2 |
| pin 8 | terminal 1 |
Categories
PCD7 / Txxx
PG5 2.0 / Profibus FMS
PG5 2.0 / Profibus DP
PG5 2.0 / Serial-S-Bus
PG5 2.0 / Profi-S-I/O
Last update: 29.05.2015 08:31
First release: 17.06.2004 11:42
Views: 22598
