MicroLogix 1400 Modbus

I'm setting up a 1400 to be a modbus TCP slave. under the channel configuration dialog box i've enable modbus on channel 1 (it already had an IP and subnet for a pre-existing TCP/IP connected HMI), which gives me a new tab. i've configured the modbus tab to define my contact and holding registers and said ok. it created my new data files (B20 Contact and N21 Holding).

what am i missing? I can't find anywhere to define the slave address in the settings. All the online help references to modbus slave address are how to configure the 1400 as a master, not a slave.

Thanks in advance.

Modbus TCP does not use a slave address. You have a UnitID which is normally 1. The master identifies slaves based on IP address and UnitID.

Can't remember off the top of my head whether the ML1400 has a configurable UnitID. Just try 1 or 254 if your master requires one to be entered.

right. i guess i was interchanging "slave" and "unit id". I can't find any settable "unit id" field in the config. I was going to try 1 by default, cross my fingers and hope it talks. I'll find out soon enough... commissioning tomorrow.

thanks for replying