So you need to know how to setup RSLinx Classic to communicate over serial with an Allen-Bradley PLC-5 so you can download or go online with RSLogix?

Well you’re in luck as in today’s article I’ll walk you step to setup through how to setup RSLinx as well as how to download from RSLogix:

Prerequisites: Before you begin, first insure your PLC-5 has serial port (not all do.)

Specifically, the new platform PLC-5/11, 5/20, 5/30, 5/40, 5/60, and 5/80 all have a 25 Pin D-Shell Serial Port.

Note that the 9 Pin D Shell on the PLC-5/10, 5/12, 5/15, and 5/25 is not a serial port but instead internally tied to the DH+ terminal block.

Next, insure you have the RSLogix 5 programming software and either the 1784-CP10 or equivalent Null Modem Cable. If your PC does not have a built-in serial port you’ll also need a USB to Serial converter.

Step 1) Start by checking Windows Device Manager to determine your PC’s serial port COM number:

Step 2) Next launch RSLinx Classic, and then under the Communications menu select Configure Drivers:

Step 3) Then from the Available Driver Types drop down list select RS-232 DF1 Devices and then click on Add New:

Step 4) Accept the default name by clicking on OK:

Step 5) Now select the COM port you looked up earlier, and check to be sure you have plugged your PLC-5 into it:

Step 6) Now click on Auto-Configure. If your cables and PLC-5 are in working condition, and your PLC-5 is set to the default DF1 protocol, then you should see the message, “Auto Configuration Successful”:

Step 7) Now click on OK to close the RS-232 DF1 Devices driver window:

Step 8) And click on Close to close the Configure Drivers window:

Step 9) Next, double click on your new driver in the RSWho window and after a few seconds you should see your PLC-5 appear under the AB_DF1-1 driver as shown below:

Step 10 Now open RSLogix 5, and then open your program file:

Step 11) Next, from the Comms menu select System Comms:

Step 12) In the popup Communications window expand your AB_DF1-1 driver and select your PLC-5:

Step 13) Then to download your program select the Download button:

Step 14) Confirm you would like to download the current program you have open into the PLC-5 you are connected to:

NOTE: The PLC-5 can only hold one program at a time, and downloading to it will erase the PLC-5’s currently loaded program. If you do not have a copy of the current program loaded in your PLC-5 you should first perform an upload and save.

Step 15) Next, if the communications settings in your offline PLC-5 file are different than the settings you are currently using you will receive a notice asking if you want to save the current setting to your offline project file:

Step 16) At this point if the Controller in your offline project is different than the one you are downloading to you will be asked to confirm the change and resize data tables:

Step 17) And if the PLC-5 was in Run Mode you’ll be asked if you would like to put it into program mode so the download can take place.

Step 18) At this point if you made any changes to your program you may be prompted to save it:

Step 19) At the end of the download process, if you still have communications with the PLC-5 controller you will be given the option of putting the controller back into the run mode (if it was in the run mode prior to downloading,) and you’ll also receive a pop-up giving you the option of going online:

NOTE: You can watch a video demonstration of this procedure below:

I hope today’s article about how to setup RSLinx Classic to communicate to a PLC-5, and then how to download to the PLC-5 using RSLogix 5 was helpful.

If you have any questions, comments, or suggestions, please feel free to post the by clicking on the “Click here to post a comment or question” link below.

Until next time, Peace ✌️ 

Shawn M Tierney
Technology Enthusiast & Content Creator

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Shawn Tierney



  1. With a 5/30 processor, can the key be in the RUN position for the automatic connection configuration to work in Rslinx. Because when connecting via CH0 I still get the message: “Falied to find the baud and priority! Check all cables and switch settings!”. Please help.

    • Yes. Now your turn:

      – Are you using a null modem cable? (DTE to DTE)
      – Did you “pin it out” to be sure it’s a null modem?
      – Does the same cable work on other PLC’s?

      If you answer yes to all these questions, check your saved PLC-5 program file to see what settings channel zero is set at – likely it is set at something other than DF1, or you’re going to have to set RSLinx up manually because your USB to Serial device doesn’t support auto-config.



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