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How to use S7-1200 Modbus library with more than one slave
Created by: Flomaster at: 10/21/2009 3:52 PM (9 Replies)
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| 10/21/2009 3:52 PM | |
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Posts: 65 Rating:
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Hi! Thank you for your reply! I have checked my test program once again. My problem as you said was in organization of modbus work: I tried to send next request when MB_Master was busy. Now my test program (it's in attachment) works better, but I still have a little problem. In test program I read data from 2 registers of device and write data to one register the same device. I read data from register 40052 and write it to register 40051. The data from register 40065 is reading only. I think this operation must take less then 1 second, but it takes 5-10 seconds. The end version of my program must read over 10 registers and write over 5 registers. And I think it would be very slowly. I sure that I have a mistake in my algorithm. Can you help me to find it? AttachmentTEST_MODBUS.zip (749 Downloads) |
Last edited by: O_Moderator at: 10/26/2009 10:57 AMLast edited by: O_Moderator at: 10/26/2009 10:27 AMLast edited by: O_Moderator at: 10/26/2009 10:27 AMnew subject after splitting Last edited by: Flomaster at: 10/23/2009 12:31 AM |
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| 10/23/2009 3:59 PM | |
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Posts: 65 Rating:
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Dear Robster ! Can you look my attachment and help me to find mistake in my program? |
This contribution was helpful to
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| 10/25/2009 3:06 PM | |
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Posts: 65 Rating:
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Thanks for all! It works fine! |
| 10/26/2009 2:46 PM | |
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Posts: 65 Rating:
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Hi, Robster. I agree with you about initialization of MB_COMM_LOAD. The latest variant of my program call this FB in Startup OB. But as you said, I can't guarantee to you that all three slaves will processed step by step. This is my main problem. But now it works correctly. Have you any ideas how to make it correctly? |
| 10/27/2009 12:24 AM | |
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Posts: 65 Rating:
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Thank you! I'll try to do it! |
| 10/4/2012 4:14 AM | |
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Posts: 65 Rating:
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Hi, friends! My project was frozen for a long time, but now it actual again. I my problem is actual again too! So, I have PLC S7-1200 and two communication networks: RS-485 and RS-232. RS-232 network has only one slave device. RS-485 network has seven slave devices and I have problem with it. I try to read and write data step by step, but about 50% of MB_Master executing finishes with errors (such as 80C8 or 8200). So I have a great delays working with each device in RS-485 network. For example, I send "Start" or "Stop" command, and device get it after 1,2 or 3 minutes! Here is a part of my project in attachment! I hope, someone show me, where is my mistake! AttachmentMODBUS_RTU_MASTER.zip (365 Downloads) |
| 10/8/2012 12:12 AM | |
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Posts: 65 Rating:
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Hi all! I think, I use MB_Master wrong in my attachment.. Can anyone help me? |
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