RS485 Output

[Dario8]

Is there any way to use the RS485 as a simple output. All I need to do is to turn a 50mA LED on with 1.85V across it whenever a counter = 0.

I have all other 16 inputs on my T44H-npn in use and I'm hoping that I wont have to either upgrade to a bigger board or add more hardware.

I'm assuming that this can be done and should be easy, considering this is a communication port, but I'm having trouble understanding how to go about this.

[support]

Unfortunately that will not be possible. RS485 is a communication port, not for driving any kind of load. In any case the RS485 ports on H and E series are slave ports only. i.e. the PLC only respond to incoming command from master. They don't initiate command out of the RS485 port. You can't use it for your intended purpose.

[cdenk]

Depending on your abilities, could build up a single chip processor like a PIC with RS-485 serial input, and the PIC would received the command, determine if it was the one on the RS-485 (assuming more than two nodes), and turn on, off or flash the LED. Kind of an overkill, but you need something to interpet what's coming across the RS-485 and then act. If there is only the 2 nodes on the RS-485, might be able to have a flip/flop toggle, but if things got out of synch, not good. If there is only that one thing to control on the pair of wires, why not just hook the pair to an output with a resistor and the LED on the other end? IS there a spare pair of wires going there?