The IC485S/GB/EU is an RS-232 to RS-422/RS-485 converter:
The information in this article applies to a range of converters:
The remainder of this article uses the name IC485S to refer to any of the above.
The converter has two switches that configures how it operates:
In RS-422 mode two pairs of wires are used to communicate with the PLC device. For example:
The communication link is full duplex. The Rx pair of wires handles data sent from the PLC to Fernhill SCADA. The Tx pair of wires handles data from from Fernhill SCADA to the PLC. Data can be sent in both directions at the same time.
To configure the IC485S for RS-422 mode:
You can use a DB-25 to DE-9 modem cable to connect the IC485S adapter to an RS-232 DE-9 port on a computer.
As an alternative you can create your own cable using this wiring:
|
IC485S |
Computer | ||
|---|---|---|---|
| TxD | 2 | 2 | RXD |
| RxD | 3 | 3 | TXD |
| GND | 7 | 5 | GND |
In RS-422 mode only the RXD, TXD and GND signals are required on the RS-232 link.
For best results use a connection cable with four wires arranged as two twisted pairs. Use one twisted pair for the transmit circuit and the other twisted pair for the receive circuit. For a long connection cable install termination resistors at each end of the cable.
Use this table to select the correct wiring between the IC485S and various PLC Devices:
|
StarTech IC485S IC485SGB IC485SEU | ||||
|---|---|---|---|---|
| 1 (TX-) | 2 (TX+) | 3 (RX+) | 4 (RX-) | |
|
Mitsubishi Melsec | RDB | RDA | SDA | SDB |
|
Omron CS/CJ DE-9 SCB41-V1 Port 2 SCU31-V1 Port 1 SCU31-V1 Port 2 SCU41-V1 Port 1 | 6 (RDA) | 8 (RDB) | 2 (SDB) | 1 (SDA) |
|
Omron CS/CJ Terminals SCU32 Port 1 SCU32 Port 2 SCU42 Port 1 | 1 (RDA) | 2 (RDB) | 4 (SDB) | 3 (SDA) |
|
Omron CP1x CP1W-CIF11 | RDA- | RDB+ | SDB+ | SDA- |
|
Omron C200H C200H-LK202-V1 | 6 (RDA) | 1 (RDB) | 5 (SDB) | 9 (SDA) |
|
Omron CPM1/2 CPM1-CIF11 | RDA | RDB | SDB | SDA |
|
Wago 750 750-312 750-315 | 7 (RxD Inv) | 2 (RxD) | 3 (TxD) | 8 (TxD Inv) |
Note: The labels applied to RS-422 connections are not consistent and vary from one manufacturer to another.
Use these guides for information about RS-422 connections on PLC Devices:
In RS-485 mode one pair of wires is used to communicate with the PLC device. For example:
The communication link is half duplex. Only one device can transmit at any one time.
In RS-485 mode only one device can transmit at any one time. Each device must enable its transmitter only when it needs to send data.
Setting SW2 to T.RTS/R.RTS configures the IC485S to control the transmit and receive functions as follows:
| RTS | Transmit | Receive |
|---|---|---|
| Inactive | Off | On |
| Active | On | Off |
To configure the IC485S for RS-485 mode:
You can use a DB-25 to DE-9 modem cable to connect the IC485S adapter to an RS-232 DE-9 port on a Computer.
As an alternative you can create your own cable using this wiring:
|
IC485S |
Computer | ||
|---|---|---|---|
| TX | 2 | 3 | TXD |
| RX | 3 | 2 | RXD |
| RTS | 4 | 7 | RTS |
| GND | 7 | 5 | GND |
For best results use a twisted pair cable. For a long connection cable install termination resistors at each end of the cable.
Connect these signals on the IC485S to the RS-484 interface on the PLC Device:
| IC485S | PLC Device |
|---|---|
| 1 (TX-), 4 (RX-) | Data- |
| 2 (TX+), 3 (RX+) | Data+ |
Use these links for information about RS-485 connections on PLC Devices:
When configuring the Mode property of a serial communication channel in Fernhill SCADA, be sure to set RTS mode to tg. For example:
Baud=9600 Data=8 Parity=E Stop=2 RTS=tg
Setting RTS=tg tells the Fernhill SCADA driver to assert the RTS signal when sending data. This in turn tells the IC485S to turn on the RS-485 transmitter during the send.
To learn how data is sent serially.
To learn about configuring serial port mode strings in Fernhill SCADA.
To learn about the editor that can edit serial port mode strings.