8/20/2014 11:54 AM | |
Joined: 9/1/2005 Last visit: 8/12/2024 Posts: 4104 Rating:
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new question published by Ico_76is split to a seperate thread with the subject connect CP441 to Modbus slave RTU devices from Schneider TRV00210 Best regards CS Moderator |
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12/2/2016 11:32 PM | |
Joined: 9/27/2006 Last visit: 8/27/2024 Posts: 12279 Rating:
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Hello Kiiza; See the information in the last part of this FAQ, concerning the ET 200M integrating a CP 341 as Modbus RTU Master (or slave):: Which hardware and software components do you need to establish communication between SIMATIC S7 stations and third-par ty devices using the MODBUS RTU protocol? https://support.industry.siemens.com/cs/ww/en/view/58386780 When you insert a CP 341 in a ET 200M configuration, the configuration of the CP only selects a number of bytes reserved for the exchanges between the Profibus master and the CP 341. This number of bytes (8, 16 or 32 bytes, depending on your communication speed requirements over Profibus-DP) has nothing to do with the number of bytes exchanged between the CP 341 and the Modbus slaves it is communicating with; these are programmed through the Loadable Driver you set up on the CP 341. It is simply to create a channel between the CP and the Profibus master. You then have to program the Modbus functions (made available through the Loadable driver and the dongle to be placed in the backside of the CP 341) in the CPU that acts as a Profibus master. Hope this helps, Daniel Chartier |
Last edited by: dchartier at: 12/2/2016 11:37:05 PM |
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12/6/2016 5:06 AM | |
Joined: 3/28/2010 Last visit: 8/26/2024 Posts: 1055 Rating:
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JBUS, for most practical purposes, can be handled as Modbus. Historically, there was a licensing issue prior to Modbus becoming an open protocol, so JBUS deviated from the Modbus spec slightly. The differences are so minor that in most cases Modbus can be used successfully. The best summary of the differences between JBUS and Modbus are on a Software Toolbox web page: http://support.softwaretoolbox.com/app/answers/detail/a_id/3402/~/jbus-protocol-vs.-modbus-protocol In case the link above goes bad over time, the details from that page are on this graphic image: https://s13.postimg.org/v6uggcgtj/Software_Toolbox_table_for_JBus_vs_Modbus.jpg One must be aware of JBUS' one based register addressing vs Modbus' zero based addressing. But unless the JBUS unit uses the slightly extended addressing scheme, Modbus should be able to address it. |
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