IP Address

[salih]

Dear All
I am using SLC500 AB-5/05 CPU
I am setting enternet connection with 3 plc
i like to know where is the IP addresses location in the MSG Block
when you are sending the data from one plc to another plc
many thanks
looking forward to hear from you very soon
salih

 

[Allen Nelson]

It's all in the wrist...

You need to change the Channel in "This Controller" from zero (defualt, and the DF1 port) to one (the ethernet port).

When you do this, the "Target Device" options change from "Local Node Address" to "Ethernet (IP) Address".

 

[Allen Nelson]

Received via PM

salih wrote on Today 12:33 PM:
Dear Allen Nelson
Thank you very much for your reply to my question
i was actually asking how can i read this IP address from PLC address. namely when we set-up Msg instruction we write the IP address as well but how can i read this address from PLC data address to the SCADA.
Example: MSG N42:0
and which word address keeps the IP address
Many Thanks
sa

If I'm understanding you correctly, you are wanting to read (and perhaps alter) the IP address that a MSG instruction is set to.

Rockwell warns against changing this information on the fly. It wouldn't surprise me if this data (just as the TON timebase) is stored in the MSG block as well as the MG data file.

Also, the MG data file structure is only valid for PLC-5s, not SLC 5/05s. For SLCs you use N-files (i.e., N42)

 

[kamenges]

You're going to like this...

The target IP address is indeed stored in the control block. The address starts at block offset 14 (N7:14 if you enter N7:0 as the control block). It is in a byte swapped ASCII format. So if you change your radix to ASCII and look in the data file, the IP adress 192.168.131.100 would show up as:
91 .2 61 .8 31 .1 00
Looks like the big endian / little endian thing. Also, the address will take up only as much room as it needs. You know that the starting point is offset 14. But unless you know the length of the IP address you will need to search for the end. 10.1.1.1 takes up a touch over half the room of 192.168.131.100.

All the other pertinent details of the message are also stored in that block in various formats.
As Allen said, I wouldn't get too trigger happy about changing these values on the fly. You could do it but you need to be EXTREMELY careful about monitoring the status of the message.

Keith