10/17/2019 12:12 PM | |
Joined: 9/27/2006 Last visit: 3/28/2024 Posts: 12249 Rating: (2660) |
Hello DarkSpike; Fist, on the S7-1200 side. There are existing instructions for Modbus RTU. Here is a link to a FAQ that should give you indications on the programming of a S7-1200 as Modbus RTU master or slave, using a CM 1241. https://support.industry.siemens.com/cs/ww/en/view/47756141 More information can be found in the Step 7 TIA Portal online help. There are also many discussions here on Modbus RTU with a S7-1200, search for them using the Search Box at the right of this page. Next, on the Altronic side, the operating instructions of the Altronic CPU-95 mention that the RS-485 port uses Modbus RTU to connect to the display module: The 791908-1 Display Module incorporates data logging and a half duplex RS-485 port which is Modbus RTU slave compliant. The protocol used follows the Modicon Modbus RTU standard. A complete listing of the Modbus register addresses is included on the CPU-95 terminal program CD, along with a PC based Modbus compatible monitoring program which can be used to access the ignition data remotely. So connection between the S7-1200 and the Altronic seems possible using Modbus RTU. What experience do you have with Modbus RTU? In case you need a presentation (or a refresher) I suggest you start by reading this excellent introduction from our friend smiffy, it has helped many of us understand Modbus concepts, addressing and functions, so it would be easier to implement Modbus exchanges on a Siemens PLC. Modbus general description: Hope this helps, Daniel Chartier Edit: Without more details, the following comment needs to be validated: the Altronic manual seems to assume that the CPU-95 acts as a Modbus master to the display. Since Modbus RTU can only have a single master on a network, you may have to think of setting the S7-1200 as a Modbus slave in your project. D.C. |
Last edited by: dchartier at: 10/17/2019 14:28:57 |
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