Seeking insights on establishing communication with MicroLogix 1200 PLC and using the Communications toggle button

Hello everyone

I'm reaching out to seek your insights and expertise regarding a challenge I'm facing with a recently acquired plant. The plant utilizes a MicroLogix 1200 PLC to control a HighService water system, and I'm encountering difficulties in establishing communication with the PLC and retrieving its program.

Here's the current situation:

  • The MicroLogix 1200 PLC is equipped with a serial port for communication, and I'm attempting to connect it to my Windows 10 computer.
  • Despite trying different USB-to-Serial adapters, including the Prolific PL230GT, I haven't been successful in establishing a reliable connection.
  • I have thoroughly checked the cabling, switch settings, and even disabled the firewall, but the issue persists.
  • I have also attempted to auto-configure the connection using RSLinx, but with no success.
During my investigation, I came across information about a Communications toggle button located on the processor of the MicroLogix 1200 PLC. The datasheet states that this button allows switching between user-defined communication configuration and default communications mode on Channel 0. The Default Communications (DCOMM) LED indicates when the controller is in the default communications mode.

In light of this, I have the following questions:

  1. Could the use of the Communications toggle button have any impact on establishing communication with the MicroLogix 1200 PLC?
  2. Should I consider toggling the Communications toggle button to potentially reset the communication settings to default values?
  3. Are there any precautions or considerations I should be aware of when using the Communications toggle button?
I kindly request your insights, suggestions, or experiences related to the use of the Communications toggle button and its potential relevance to resolving the communication issues I'm encountering with the MicroLogix 1200 PLC.
Dear LuisLarraga
You can push the toggle button then DCOMM light will appear and you can communicate the PLC because you don't know previous user defined configuration and again you can push and it will bring you back to previous setting and DCOMM light will be off. its just switching between user defined and default parameters of communication.
default parameters are Baud rate 19.2K, Parity None, Source ID 1 and Stop bit 1.