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CP341 Modbus RTU connection to DCS over Modbus TCP/IP

Created by: Techy at: 4/21/2007 1:49 PM (8 Replies)

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4/21/2007 1:49 PM	Rate (0)
Techy Posts: 86 Rating: (2)	Hello, We have a CP341 Modbus module connected to DCS using a MOXA gateway 5150 ( I/p RS 485 & output is TCP/IP). However when trying to access bits./ register I am getting yime out error. My question is does the TCP/IP allow the Modbus RTU data to be passed intact? We are looking for a gateway to act as an envelope to the RTU based command over TCP/IP. The Moxa pings to the DCS showing that the ethernet connectivity is OK. It asks for Connection type setting which is default Modem type. I changed this to TCP/IP but still facing the problem. Any advice welcome Thanks, Techy
Techy Posts: 86 Rating: (2)
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4/23/2007 10:04 AM	Rate (0)
Wizard Diamond Member Joined: 4/24/2006 Last visit: 3/23/2023 Posts: 8586 Rating: (1126)	Hi Techy, I don't know anything about the MOSA gateway. I'm sorry I can't help you about that problem But I wonder have you seen this faq: http://support.automation.siemens.com/WW/view/en/22660304 Perhaps it's usefull. Best regards, Wizard

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4/23/2007 10:07 AM	Rate (0)
J_Bell Posts: 5822 Rating: (411)	Hello Techy, well I have to admit I have no experience with CP 341 or Modbus but as you say you use a Converter by MOXA, do they say anything about it or do they have any diagnostics feature in there? Have you monitored the Traffic on the RS485 Segment yet? On the other hand, there is the following possibility. The CP 343-1 (Ethernet CP) is capable with the Modbus TCP Driver to act as Modbus Device. Have you thought about this possibility? Best regards J_Bell
J_Bell Posts: 5822 Rating: (411)
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4/27/2007 9:27 PM	Rate (0)
Scott Bronze Member Joined: 10/23/2005 Last visit: 3/31/2020 Posts: 81 Rating: (8)	Hey Techy, 1.)Make sure you have the driver configured correctly. 2.)You have to designate "M" memory for the bits to be written and read from. 3.)You must have FB 80 from theModbus library running. I understand you can do a functions 3,4,6,16without it running or in your logic, but itneeds to be running for functions 1,5,15. Hope this helps

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5/12/2007 11:36 AM	Rate (0)
Techy Posts: 86 Rating: (2)	Thanks guys for the help! I am replying back a bit late as I was away I was able to solve the problem by setting the Moxa to Terminal server mode. Thanks, techy
Techy Posts: 86 Rating: (2)
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5/13/2007 6:36 PM	Rate (1)
Late Platinum Expert Joined: 1/7/2006 Last visit: 2/16/2023 Posts: 2705 Rating: (311)	Hi Techy, It could be that the CP 343-1 with the OPEN TCP MODBUS driver from Siemens is cheaper and better to understand then the way you have done it now. Have you considered that...
	I hope that the answer will help, if you have still questions, don't hesitate to ask me. All the best, Late Never say never, think in solutions, not in trouble......
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5/14/2007 5:45 PM	Rate (1)
Techy Posts: 86 Rating: (2)	Late Hi Techy, It could be that the CP 343-1 with the OPEN TCP MODBUS driver from Siemens is cheaper and better to understand then the way you have done it now. Have you considered that... Late, I was not aware that there is Open TCP Modbus driver that installs on the CP343-1. Thanks for the information though, will use it in future projects Techy
Techy Posts: 86 Rating: (2)
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5/19/2007 1:56 PM	Rate (0)
Late Platinum Expert Joined: 1/7/2006 Last visit: 2/16/2023 Posts: 2705 Rating: (311)	Techy Late, I was not aware that there is Open TCP Modbus driver that installs on the CP343-1. Thanks for the information though, will use it in future projects Techy Hi Techy, So we are learning all the time and with a little help it is easier to get it into the right way.
	I hope that the answer will help, if you have still questions, don't hesitate to ask me. All the best, Late Never say never, think in solutions, not in trouble......
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5/30/2007 12:35 PM	Rate (0)
Techy Posts: 86 Rating: (2)	Late, thank you.
Techy Posts: 86 Rating: (2)
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