RJ45 to DB9 Pinout Help

Attached is what I got on a Horner HMI. I'm trying to just establish basic modbus comms. Could someone tell me what pin out I should use on a standard serial cable to this RJ45 connection for RS-232 comms?

Thanks

...I'm connecting to a MicroLogix 1400; Channel 2 serial set to Modbus Slave, if that makes any difference.

There is no such a thing as a standard serial cable.

You need to find the pinout for whatever you are hooking up your HMI to.

Then TxD on one side goes to RxD on the other.
RxD goes to TxD.
CTS goes to RTS (if you have one)
RTS goes to CTS (if you have one)

If one side doesn't have RTS/CTS you need to make a connection from RTS to CTS on the one that have it. You could also disable hardware handshaking if you have such a setting.

PS. And 0V to 0V (sometimes called GND).

Also, at least some of the Horner HMIs have a protocol driver for DF1. That's going to be somewhat easier to deal with than modbus if you have that as an option.

Dravik said:

Also, at least some of the Horner HMIs have a protocol driver for DF1. That's going to be somewhat easier to deal with than modbus if you have that as an option.

Click to expand...

Yeah, I have noticed that. And also seen it in the manual, however I can't get it as a selectable protocol, even after reinstalling the drivers from Horner. I can with other HMI models but not that one for some reason.

Thanks guys. I had the wiring correct, but the internal ladder logic in the Horner HMI was timing out, and crashing the comms ports.

Yeah, the Horner PLCs can be a bit tricky to open the comport and assign it to rs485, since it's all done in the ladder logic