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MODBUS w/S7-1200

Created by: Import-User-1 at: 2/1/2010 12:20 PM (7 Replies)

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2/1/2010 12:20 PM	Rate (0)
Import-User-1 Posts: 3609 Rating: (29)	Import of a Technical Question of an User Guest wrote: Hello, I'm a distributor for Siemens Process Instrumentation and I have to rush a project using MODBUS communications in the S7-1200. I can't get the DB to work in my MB_SLAVE block. Is there a step by step guide to show me how to establish modbus communications? Thanks, Mark
Import-User-1 Posts: 3609 Rating: (29)
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2/1/2010 12:53 PM	Rate (0)
UMENCHO Diamond Expert Joined: 3/21/2006 Last visit: 12/2/2024 Posts: 10229 Rating: (1181)	Hello, Look at /tf/WW/en/Posts/33967#top Hope this will helps. Best regards, Hristo Mihalev

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2/1/2010 3:13 PM	Rate (0)
Robster Gold Member Joined: 5/28/2008 Last visit: 10/23/2024 Posts: 1343 Rating: (141)	Have you configurate your RS485 Port for working on modbus by calling MB_COMM_LOAD in startup-OB?

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2/1/2010 4:18 PM	Rate (0)
Arnold78 Posts: 5 Rating: (0)	Thanks for the link. I beleive this sample program has provided enough details to show the error of my ways. I appreciate the quick response. Mark
Arnold78 Posts: 5 Rating: (0)
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2/1/2010 5:32 PM	Rate (0)
Arnold78 Posts: 5 Rating: (0)	Sorry, I still have problems. I made sure to take off the checkmark for symbolic as per some instrunctions but still can't get my MB_HOLD_REG to work, keeps popping up with that error below: Network 1,Only data blocks based on SDT or UDT can be used as actual parameters for data type VARIANT parameters. I'm trying to compare the program from the link and can't seem to find the difference between. Maybe the creation of my DB is incorrect. Looks the same but probably missing something.
Arnold78 Posts: 5 Rating: (0)
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2/1/2010 8:21 PM	Rate (0)
Arnold78 Posts: 5 Rating: (0)	Well moving forward, pass the compililng stages now. My device is still not talking. For the RS485 Module, Can I just used pin 3, 8 and 5? (A, B, GND) That's all my other device needs for communication. another update - my port status says: 8180 (Invalid Port ID value)
Arnold78 Posts: 5 Rating: (0)	Last edited by: Arnold78 at: 2/1/2010 8:34 PM
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2/2/2010 9:40 AM	Rate (0)
Robster Gold Member Joined: 5/28/2008 Last visit: 10/23/2024 Posts: 1343 Rating: (141)	There are many things seems to be wrong. I think best way is to zip you project and attach it here. It is difficutl to know what you have done with the DB. Normally this should be not the main problem. To your other questions: Wireing is like you wrote. Standard RS485. Wrong Port ID means, you haven't entered the real PORT Number at MB_COMM_LOAD. It's very easy, click at the input PORT and search your RS485 Modul from the list. Normally it should have ID 11, 12 or 13. Depending on which place it is in hardware configuration. regards

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2/3/2010 12:20 AM	Rate (0)
Arnold78 Posts: 5 Rating: (0)	Here's my modbus test database. Let me know. I know it's going to be simple. Attachment Modbus.zip (530 Downloads)
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