krimson

i used profibus cable.. but i will play with it with only using the netw function... maybe having a read on one and a write on the other was throwing it off. i ended up using a quick fix by simply running a Q on PLC1 and 2 to an I on PLC3 (after proper 110/24v conversions) it works like i want it to, but i would like to be able to avoid that in the future.

that is exactly what i did, and now i can actually get information sent across, but i was a little hazy on what all to put.. so i did a netw on plc1 to plc3 and a netr on plc3 to plc1 and i see the data getting transferred, but its not holding its value... it gets a quick shot of the right data, then goes to zero... then it flashes again the right value, and goes to zero... i dont know if i need to have both the netw and netr if i dont need to send anythng BACK to plc1.. i just need it to read.. but, do i need a write on one end and a read on the other, or just a write on the one OR a read on the other?

well what i am trying to do is send a VW900 from plc1 to plc3 and i was playing with the netw/netr functions, but they only send bits... not words... since i am actually moving C1 (a timer) into VW900 i was almost thinking of trying to send a bit with netr/w and hack a timer on the other end... but being a hack, its not a very good solution and will most likely get way out of sync and end up being far too much hassle than its worth. ive read about using global tables, but i am very unfamiliar with that.. i go on my symbol tables and in USR1 i make a VW900 entry, and then try and see if PLC3 reads the data, and it just reads as 0, so that is a no... im a little new at all of this, so i am a little more than lost!!!

i am trying to achieve this same thing with s7-200s over profibus, and i cannot for the life of me figure out how to have PLC_3 read data from PLC_1 or PLC_2.

what did you find was your solution? this is the problem i am having.. i cant figure out to send data from one PLC to another... thanks!