The Advantech ADAM-4520 is an RS-232 to RS-422/RS-485 converter:
The converter can be configured to operate in these modes:
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+/Rx- pair of wires handles data sent from the PLC to Fernhill SCADA. The Tx+/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 ADAM-4520 for RS-422 mode:
You can use any RS-232 DE-9 male to female extension cable to connect the ADAM-4520 to a computer.
As an alternative you can create your own cable using this wiring:
ADAM-4520 |
Computer | ||
|---|---|---|---|
| TxD | 2 | 2 | RXD |
| RxD | 3 | 3 | TXD |
| GND | 5 | 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 ADAM-4520 and various PLC Devices:
|
Advantech ADAM-4520 | ||||
|---|---|---|---|---|
| TX+ | TX- | RX+ | RX- | |
|
Mitsubishi Melsec | RDA | RDB | SDA | SDB |
|
Omron CS/CJ DE-9 SCB41-V1 Port 2 SCU31-V1 Port 1 SCU31-V1 Port 2 SCU41-V1 Port 1 | 8 (RDB) | 6 (RDA) | 2 (SDB) | 1 (SDA) |
|
Omron CS/CJ Terminals SCU32 Port 1 SCU32 Port 2 SCU42 Port 1 | 2 (RDB) | 1 (RDA) | 4 (SDB) | 3 (SDA) |
|
Omron CP1x CP1W-CIF11 | RDB+ | RDA- | SDB+ | SDA- |
|
Omron C200H C200H-LK202-V1 | 1 (RDB) | 6 (RDA) | 5 (SDB) | 9 (SDA) |
|
Omron CPM1/2 CPM1-CIF11 | RDB | RDA | SDB | SDA |
|
Wago 750 750-312 750-315 | 2 (RxD) | 7 (RxD Inv) | 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. The ADAM-4520 supports two modes for enabling its RS-485 transmitter:
| Mode | Description |
|---|---|
| Automatic | The ADAM-4520 turns on the RS-485 transmitter by listening to received data on the RS-232 interface. For this mode to work correctly, SW1 and SW2 should match the Baud Rate and Data Framing of the RS-232 link. If you want to change the Baud Rate or Data Framing you have to open the ADAM-4520 and change switch settings. |
| RTS Control | The ADAM-4520 turns the RS-485 transmitter on when the RTS signal is asserted. The Baud Rate and Data Framing of the link can be changed without opening the ADAM-4520. |
The remainder of this section describes how to set up RTS Control mode.
To configure the ADAM-4520 for RS-485 mode using RTS Control:
You can use any RS-232 DE-9 male to female extension cable to connect the ADAM-4520 to a computer.
As an alternative you can create your own cable using this wiring:
|
ADAM-4520 |
Computer | ||
|---|---|---|---|
| TxD | 2 | 2 | RXD |
| RxD | 3 | 3 | TXD |
| GND | 5 | 5 | GND |
| RTS | 7 | 7 | RTS |
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 ADAM-4520 to the RS-484 interface on the PLC Device:
| ADAM-4520 | PLC Device |
|---|---|
| Data+ | Data+ |
| Data- | 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 ADAM-4520 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.