Micrologix 1500 PLC, Cannot connect via RSlinx

I have a Micrologix 1500 that I cannot connect via micrologix/rs232 DF1 cable/driver. I have tried 3 different laptops, tried direct connect with micro to rs232. I tried micro to 1747-UIC to rs232.. I cannot "see" the micrologix 1500 at all. It is communicating fine with a proface hmi, unit works fine, I'm just trying to troubleshoot an occasional error that comes and goes. I'm frustrated.

Any suggestions?

Which cable are you using?

Which port (channel 0 or 1)? Are you using the same port that the HMI is using and if so how is the HMI’s port configured?

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I am using the 1761-cbl-pm02 ser c pc to micrologix cable, I have tried channel 0 to channel 10 with no luck so far. I called the manufacturer of the machine, Tallyrand, he said they lock the plc so we cant get in them. So now we have a service call out to them. I would like to be able to get in the plc, but doesn't look like I will be able to.

Make sure you go to your Start>Devices and Printers and check which port the PM02 cable is using, and make sure the associated drivers are installed properly. If the drivers aren't installed, it won't show up.

Com port is correct. I can communicate with other plc's with current set up, just not this one

Is this a single-port 1764-LSP or a dual-port 1764-LRP ?

Which port is the HMI connected to ? Which port are you trying to connect to ?

One diagnostic test you can perform is to disconnect the HMI from the controller and watch the serial port indicator LED. If it stays off, the protocol is very likely DF1. If it blinks about once per second, the protocol is DH485.

The usual way to connect to a MicroLogix 1500 with an unknown protocol is to use the Channel 0 serial port and press the DCOMM button until the DCOMM LED comes on indicating that the controller has been temporarily switched to DF1 Full Duplex 19200 baud on the Channel 0 (built-in, round, min-DIN8) port.

Pressing the button again returns the Channel 0 port to its configured settings in the PLC program.

I’m curious on how they “Lock” the PLC. I’ve not seen or heard of that before. I call BS unless someone else has heard of this being done and if so how is it done?

The right way to "lock" a MicroLogix is to turn off the "Allow Future Access" bit, set every data table except the HMI interfaces to Read-Only, and tell your customer about it during the purchase process.

"Locking" just a serial port... you could simply set it to Disabled. But the Channel 0 DCOMM feature will always be available.

Thanks for all your replies... we are working on it today, so I will get more info on it. But it is a single, with a micro to dh(485?) adapter ( goes to the Proface HMI ), again I will get more info today. Right now I am in the office waiting for the service rep to come in...... thanks guys

Sorry for the late reply, Thanks Ken, I was able to get into the PLC with your advice. But there was a password to get in RS500, so the builder ended up fixing it.