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Need to communicate between a Koyo ECom 100 module and S7-1200

Created by: kevsticle at: 1/25/2010 2:16 PM (5 Replies)

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1/25/2010 2:16 PM	Rate (0)
kevsticle Posts: 8 Rating: (0)	Has anybody tried talking ModBus/TCP yet? All I can get is a connection then an 80C4 with no data at all :(. Need to communicate between a Koyo ECom 100 module and S7-1200. I don't understand why all I can get is a connection which then fails if a protocol can really be written on this unit? I cannot rely on a PC as our plants are too critical! Any comments would help me and others I am sure...
kevsticle Posts: 8 Rating: (0)	Last edited by: O_Moderator at: 1/26/2010 10:22 AM new subject after splitting from /tf/WW/en/Posts/32806#top
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1/28/2010 3:38 PM	Rate (0)
Kaulquappe Posts: 3093 Rating: (319)	Hello kevsticle, does the S7 act as client? Then you have to use remote port 502. If the S7 acts as server, the local port has to be 502. Regards, Kaulquappe
Kaulquappe Posts: 3093 Rating: (319)
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1/28/2010 4:54 PM	Rate (0)
Robster Gold Member Joined: 5/28/2008 Last visit: 3/1/2023 Posts: 1343 Rating: (139)	At the moment, S7-1200 can't handle Modbus/TCP communication. Only Modbus/RTU!. I think that is your problem

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1/29/2010 10:30 AM	Rate (0)
Kaulquappe Posts: 3093 Rating: (319)	Hello Robster, ModbusTCP is based on TCP native and S7-1200 is able to communicate via TCP native. So you can set up a PLC program which realises the Modbus frames. Regards, Kaulquappe
Kaulquappe Posts: 3093 Rating: (319)
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1/29/2010 12:31 PM	Rate (0)
kevsticle Posts: 8 Rating: (0)	Thanks everybody for your advice! I have it working now - lots of work to do but basic talking is happening. It is to do with the perculiar way that TRCV length works. A length of 0 (ad-hoc) will try to receive the data length of data when the output is pointed to an array of bytes. If you set the length to the correct length this works fine (but modbus has variable length data depending on the remote write command). If you set the length to 0 (ad-hoc) and send the output to a struct, all is fine and you can use as much or as little of the struct as you like so long as it is big enough for the data that comes in (+header). I havent tried other data types yet... I am suprised it works like this and cannot see a logical reason for it but still... Good luck to anybody else trying this! Kev.
kevsticle Posts: 8 Rating: (0)
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3/2/2010 9:42 PM	Rate (0)
Rohit Bhatia Posts: 15 Rating: (0)	Hi! I'm not sure but I guess that it's not the data type but the total data length that matters. I had the issue initially of the CPU going into the STOP mode because I had not created sufficient entries in the receiving DB toaccommodatethe data coming in. Anyhow, that issue is now resolved but I thought it might be helpful to others if I share this information here. Regards.
Rohit Bhatia Posts: 15 Rating: (0)
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