SLC5/05 to 5/05 MSG instruction

Hello all, after searching I can see many posts on the MSG instruction but not one with exactly with the same problem as I am having.....( i think )

Firstly we have multiple 5/05's and our plant network all of which work fine.

A few months ago I added a message instruction into one of them (lets call the plc 1) to read a data file from another (plc 2) ( I read N250:0), control bits etc are set and IP addresses and subnet are correct, today I added a MSG instruction in plc 2 to read N20:0 in plc 1, but for some reason it won't read it. For example in plc 1 I can set N20:0/0 to 1 but in plc 2 N20:0/0 remains 0.

I take a copy of the ladders tomorrow and post them up to try and clear things up a bit

Thanks
Chris

Yes posting your .RSS file will help the forum help you.

Is the anything writing to ( controlling) that bit (n20:0/0 in PLC 2?

"..... It won't read it".

why you monitor this new MSG instruction are you seeing the DN or the ER bits go true?

And let's make sure we have this correct. PLC2 is going out on the network to PLC1 and reading N20:0 and bringing that data back and storing it in PLC2 at N20:0. Is that right?

Can you go into N20:0 on PLC2 and manually type a number (like 1234) into it and then execute the MSG? If so, do you still have 1234 or did that get overwritten?

OG

Update !

I have added an instruction from the free running clock in front of my message instruction in both plc's( i did have the msg instructions true all the time ). The data files are now being read as expected (although the 1st plc read without any problems before I added this....)



Thanks
Chris