Allen Bradley MicroLogix 1200 Connection Guide

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This article is a guide to connect an Allen Bradley MicroLogix 1200 PLC to Fernhill SCADA.

The Allen Bradley MicroLogix 1200 PLC has one or two serial ports which can be used to communicate with Fernhill SCADA.

Note: Only selected models support the Prog/HMI port.

To connect a MicroLogix 1200 PLC to Fernhill SCADA these steps are required:

  1. Obtain a connection cable and connect the MicroLogix 1200 PLC to a Windows Computer running RSLogix 500.
  2. Configure the MicroLogix 1200 PLC using RSLogix 500.
  3. Configure Fernhill SCADA.

Connection Cables

The MicroLogix 1200 PLC can connect directly to a serial port on a PC. The serial port on a PC is usually a 9 pin D-subminiature connector. These cables are suitable to connect the PLC to a computer with a 9 pin D-subminiature connector:

As an alternative you can create your own cable using this wiring:

MicroLogix 1200

8 pin mini-DIN plug wiring side shown
D-Subminiature connector DE-9 socket wiring side shown
DCD 5 1
4 + 6 DTR + DSR

Note: All other pins not shown in the above diagram have no connection.

Configuring the MicroLogix 1200 Serial Port using RSLogix 500

You can use RSLogix 500 to configure the MicroLogix 1200 Serial Port.

  1. Open a project in RSLogix 500 and in the Project window select Channel Configuration:
    Channel Configuration selected in RSLogix 500

  2. Double-click the Channel Configuration branch to open the Channel Configuration window:
    MicroLogix 1200 channel configuration window

    Note: The Fernhill SCADA Allen Bradley Driver supports DF1 Full Duplex and DF1 Half Duplex Slave.

  3. Select the Channel 0 tab:
    MicroLogix 1100 channel 0 configuration tab

    Field configuration notes:

  4. Click OK to save the configuration. If you have changed Channel 0 configuration away from the defaults, you may receive a warning about loss of communication. Ignore the warning and, after communication is lost, change the configuration of the AB_DF1 device in RSLinx to match.
  5. If you change the communications settings away from the default it is quite easy to lose communication from both Fernhill SCADA and RSLinx. You can recover from this situation using Communications Toggle Push Button located near the Channel 0. For more information refer to the MicroLogix 1200 Programmable Controllers User Manual 1762-UM001.

Configure Fernhill SCADA

There are two methods to configure Fernhill SCADA to communicate with a MicroLogix 1200 PLC:

Manual Configuration

The default communication settings for Channel 0 on the MicroLogix 1200 are:

Baud Rate19200
ProtocolDF1 Full Duplex
Error CheckCRC
Node Address1

The communication settings for Prog/HMI port are:

Baud Rate19200
ProtocolDF1 Full Duplex
Error CheckCRC
Node Address1

The Fernhill SCADA configuration that corresponds to the defaults for Channel 0 and the Prog/HMI port is:

Allen Bradley Serial Port
ModeBaud=19200 Parity=N Data=8 Stop=1
ProtocolDF1 Full Duplex
Allen Bradley PLC
Destination Node1

Further Information

Allen Bradley serial channel

For information about Allen Bradley serial channel configuration.

Allen Bradley PLC

For information about Allen Bradley PLC Tag configuration.

Serial Communications

For background information on serial communications.

Allen Bradley Driver

For information about the Allen Bradley Driver.


For the meaning of terms used in Fernhill SCADA.