Input Device Identifier

Hello, all!

I have a couple of foolish (no smarts) trailers with conveyors. These are controlled by AB PLC when connected using a connector. Right now there's just a jumper on a pin that links 24vdc to a PLC input to indicate that a trailer is connected.

Given that I cannot expand or change the connector and only 2/3 pins. Could you please recommend some sort of identifying device so that I know which trailer is connected exactly?

My current idea is to replace jumpes with resistors of unique values and read the current/voltage on an AI card...

Thank you.

your idea of using resistors would certainly be the easiest/cheapest idea, but depending on the connection and how clean it is kept, and how many trailers you need to identify, may not be a very reliable method.

Instead of using the plugs, perhaps you could embed an RFID chip in the trailer, and a scanner in the dock. You might even be able to embed the RFID inside the plug for the trailer. You could, of course still use the plug as positive verification that the trailer is in position.

Dhitzfelder said:

your idea of using resistors would certainly be the easiest/cheapest idea, but depending on the connection and how clean it is kept, and how many trailers you need to identify, may not be a very reliable method.

Instead of using the plugs, perhaps you could embed an RFID chip in the trailer, and a scanner in the dock. You might even be able to embed the RFID inside the plug for the trailer. You could, of course still use the plug as positive verification that the trailer is in position.

Click to expand...

Do you happen to know if there's a wired equivalent?

You can use a programmable relay like this : https://www.ebay.com/itm/Programmab...mer-Relay-Trigger-Switch-Module-/192017554546

Then each of the conveyors should generate a different sequence of on-off pulses, for example with a long pause off state followed by a number of pulses different for each conveyor.

Although one drawback that I see is that the output relay is mechanical, it would be better if it were solid state .... maybe it can be changed

Why not add another connector, use a dummy cable and link the pins in binary i.e. 001 = 1 010 = 2 011 = 3 100 = 4 etc. the cable is just a tie to the trailer.
so that the operator has to plug in the two connectors (make sure they are not interchangeable).