Advantech ADAM-4520 Communication Guide

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Introduction

The Advantech ADAM-4520 is an RS-232 to RS-422/RS-485 converter:

ADAM-4520 RS-232 to RS-422/RS-485 converter

The converter can be configured to operate in these modes:

RS-422 mode

In RS-422 mode two pairs of wires are used to communicate with the PLC Device. For example:

ADAM-4520 showing an RS-422 point to point link

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.

Adapter setup

To configure the ADAM-4520 for RS-422 mode:

  1. Turn the ADAM-4520 over to show the reverse side.
  2. Remove the two small back screws to release the cover.
  3. Turn the ADAM-4520 over and remove the front cover.
  4. Set SW2-10 to ON. Set all other SW2 switches to OFF.
    ADAM-4520 SW2 configured for RS-422 mode.
  5. Replace the front cover.
  6. Turn the ADAM-4520 back over and replace the two small black screws.

RS-232 Computer Communication Cable 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
D-Subminiature connector DE-9 plug wiring side shown
Computer
D-Subminiature connector DE-9 socket wiring side shown
TxD22RXD
RxD33TXD
GND55GND

In RS-422 mode only the RXD, TXD and GND signals are required on the RS-232 link.

RS-422 Connection

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:

RS-485 mode

In RS-485 mode one pair of wires is used to communicate with the PLC device. For example:

ADAM-4520 showing an RS-485 multi-point link

The communication link is half duplex. Only one device can transmit at any one time.

Adapter Modes

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:

ModeDescription
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 setup RTS Control mode.

Adapter Setup for RTS Control Mode

To configure the ADAM-4520 for RS-485 mode using RTS Control:

  1. Turn the ADAM-4520 over to show the reverse side.
  2. Remove the two small back screws to release the cover.
  3. Turn the ADAM-4520 over and remove the front cover.
  4. Set SW2-1 to ON. Set all other SW2 switches to OFF.
    ADAM-4520 SW2 configured for RS-485 RTS control mode.
  5. Replace the front cover.
  6. Turn the ADAM-4520 back over and replace the two small black screws.

RS-232 Computer Communication Cable for RS-485 Mode using RTS Control 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
D-Subminiature connector DE-9 plug wiring side shown
Computer
D-Subminiature connector DE-9 socket wiring side shown
TxD 2 2 RXD
RxD 3 3 TXD
GND 5 5 GND
RTS 7 7 RTS

RS-485 Connection

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-4520PLC Device
Data+Data+
Data-Data-

Use these links for information about RS-485 connections on PLC Devices:

Fernhill SCADA Serial Port Mode

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.

Further Information

Serial Communications

To learn how data is sent serially.

Serial Port Mode String

To learn about configuring serial port mode strings in Fernhill SCADA.

Serial Port Mode Editor

To learn about the editor that can edit serial port mode strings.