RSLogix5000 MSG Instruction

Hi Guys!

I've been asked to make a simple interface to change parameters in a VFD (Danfoss), it is quite simple done using the MSG instruction. But what was requested was some kind of AOI where you could just type in the IP address of the VFD, the parameter number and then choose if it should read or write the parameter.

OK I thought, I'll just use the MSG instruction, inside an AOI!

But this turned out to be a bit difficult. All the Class, Instance and functions are available in the control tag for the MSG instruction. But the IP adress is apparently not. I have found that it is a string but have not been able to locate the actual tag yet.

So my question is this:

Have any of you ever tried something like this?

Or an idea on where I should start?

Or perhaps even another approach to communicating with the VFD?

Best regards,

Michal_dk

If you look at your tag for the message, the ip address is stored as an ascii data type within the tag at (Base tag name).Path.Data[nn] . I have not tried doing what you are attempting, but an AOI may do the job. Where are you entering the info from(HMI, RSLOGIX, Thumbwheel)? The method you use will make some paths easier than others as far as programing.

Mark Snodgrass

Hi Mark!

Primarily I'll be using RSlogix.

Yes I see the MSG.Path, I think my problem was I was looking to add the IP address from inputs to the AOI.
I'll try using a UDT instead and use the tag directly for addressing.

Also found this thread:

http://www.plctalk.net/qanda/showthread.php?t=46281

Gives a little help too.

Best regards,

Michal_dk