9/2/2019 1:29 PM | |
Posts: 20 Rating:
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Hi! I need to have multiple devices with the RS485 interface communicating with an S7-1200 CPU 1215C PLC (using a communication module CM1241). Hardware-wise, it is possible to have those devices sharing the same bus, and both the device and the communication module have RS485 interfaces. However, I realize that some of the devices (for example, this distance sensor https://docs-apac.rs-online.com/webdocs/1534/0900766b8153436e.pdf) don't support Modbus RTU protocol (they use another protocol, specified in the datasheet). I would like to know if it is possible to configure the communication module and/or the PLC to accept other communication protocols. Thank you in advance! ------------------------------------------------------------------------------------------ |
Last edited by: Jen_Moderator at: 09/03/2019 06:22:01New subject after splitting |
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9/2/2019 2:40 PM | |
Joined: 9/27/2006 Last visit: 8/28/2024 Posts: 12280 Rating:
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Hello Maria; The suggested way to "create" your own protocol on a CM 1241 would be to use the Freeport mode. Freeôrt is a freely programmable, frame-based protocol, very close to the ASCII protocol. You simply define the frames you need to send and receive,m the start-of-text and end-of-text characters (or the number of characters to be transmitted) and use the SEnd/Receive functions for the CM to communicate with your serial partner. CM PtP - Configurations for point-to-point connections https://support.industry.siemens.com/cs/ww/en/view/59057093 Study this document's information on Freeport before asking more questions, please. Hope this helps, Daniel Chartier |
Last edited by: dchartier at: 09/02/2019 14:41:09 |
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9/3/2019 11:37 AM | |
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Thank you for your replies! All sensors on the bus have the same protocol (different from Modbus RTU). |
This contribution was helpful to
1 thankful Users |
9/3/2019 12:46 PM | |
Joined: 4/28/2015 Last visit: 2/7/2024 Posts: 10533 Rating:
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aaaah understand, thnx for answer... |
With best regards... |
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9/3/2019 9:31 PM | |
Posts: 20 Rating:
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Thank you very much for your reply! I had not thought about those problems, but you're right. Thank you! I found a similar sensor (http://image.dfrobot.com/image/data/SEN0002/URM04V2.0Mannual1.1.pdf) that has an RS485 interface, which allows having up to 32 devices connected (according to the datasheet). In the communication protocols section, they include the slaves' addresses in the data frames. So, I guess the problem of identifying from which slave comes the data on the bus is solved (?). Also, the synchronization is ensured by having the master initiating communication with one device at a time. Each sensor only places its data on the bus when requested by the master. The master waits for the data and, only after receiving it, initiates communication with a second device (?). Please correct me if I'm wrong. Thank you in advance! |
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