2/28/2017 9:01 AM | |
Posts: 49 Rating: (1) |
HI, Can i know , do really need the dongle for the ASCII protocal. If we using modbus RTU that time only we need Doggle. correct. i donot about this so i am asking. yesterday i got the 16#301 error. in the manual it was showing parameter error or wiring error i have modified the program for the communication that program i didnot checked. today only i am going to check. so if have error please update me. Here i have attached the program and the screenshot. if my program have any error please update me Attachmentprogram and screenshots.zip (411 Downloads) |
2/28/2017 9:26 AM | |
Posts: 49 Rating: (1) |
Hi, Sorry. no modbus ASCII. it was ASCII protocol. Slave device accept ASCII protocol Update: ok another question, you've mentioned from yesterday you have error, so you have communication established before with Slave via Modbus ASCII protocol and your CP341? - i have used ascii protocal. with cp-341 it was showing error. ASCII it was working in modbus Poll software Device detail is - TC202a , Manufacture is Thermon AttachmentScreenshots.zip (367 Downloads) |
2/28/2017 10:58 AM | |
Posts: 49 Rating: (1) |
hi, ok thanks for your concerns tomorrow i will check with the dongle and update you what is status. |
3/1/2017 10:23 AM | |
Posts: 3093 Rating: (323)
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No, they are different Regards, |
3/1/2017 12:55 PM | |
Posts: 3093 Rating: (323)
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Hello Duris, The dongle for ModbusRTU master and ModbusRTU slave are identical and the dongle for ModbusASCII master und ModbusASCII slave are identical. By the way, ModbusASCII can only be used with the old versions of CP341. Regards, |
3/1/2017 3:02 PM | |
Posts: 49 Rating: (1) |
Hi, Thanks for your information. we have already purchased later version module (1CH02). and Modbus Master (RTU) license. Can you help me how to solve this issue. Because we cannot use Modbus ASCII in the later version module. that device only accept modbus ASCII. please. |
3/4/2017 10:45 AM | |
Joined: 12/1/2009 Last visit: 9/5/2024 Posts: 672 Rating: (147) |
Dear PlUg & PlAy, when it comes to Modbus a S7-300 is not really a good choice. The CP341 + license dongle is by far the most expensive solution. Anyway, these are your options now:
Best Regards. TIBI68 |
Last edited by: TIBI68 at: 3/4/2017 11:00:48 AMGive us your feedback and show us your respect! |
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3/5/2017 8:39 AM | |
Joined: 12/1/2009 Last visit: 9/5/2024 Posts: 672 Rating: (147) |
Helpful links: The MODBUS Bible: http://modbus.org/docs/PI_MBUS_300.pdf LRC/CRC Online calculation for verification: http://www.scadacore.com/field-applications/programming-calculators/online-checksum-calculator/ Best Regards. TIBI68 |
Give us your feedback and show us your respect! |
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3/5/2017 8:59 AM | |
Posts: 49 Rating: (1) |
hi, thanks for your concerns. Ok, i check with software and i will update the status |
3/5/2017 3:21 PM | |
Joined: 4/28/2015 Last visit: 2/7/2024 Posts: 10533 Rating: (820) |
Hello, again pls check also my pictures, probably this is only example. If we take your mentioned frame that you've build (mentioned in some previous post) with register number hex 65, frame can be different to my previous. Look pls to new zip attachment, I was preparing this due your mentioned required 101 address. Attachmentmb_ascii_test.zip (264 Downloads) |
With best regards... |
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3/6/2017 3:48 PM | |
Posts: 49 Rating: (1) |
hi, Thanks to Duris, Danw, TIB I saw the message frame structure in the Modbus Poll. i have attached the screenshot .. I cannot see the structure in the Simply modbus slave. so i dconfirmed with the modbus poll frame structure and directly perform the sequence from PLC and Slave. Initially TX only Blinked then i swap the wires. now TX and RX was Blinking. once again i need your help to decode the received message. i have attached the screen shot for the received message. i donot know how to assign that data byte received values. I have filtered the start, slave ID, Function Code, Byte Count, LRC, CR but the in between idont know how to swap and get the values. Please help me to update this one AttachmentModbus_TX_RX_Detail.zip (211 Downloads) |
This contribution was helpful to1 thankful Users |
3/7/2017 3:19 PM | |
Joined: 4/28/2015 Last visit: 2/7/2024 Posts: 10533 Rating: (820) |
Hello PLUG, look to this interesting topic, also some good sugestions and informations you can find there. It talks about other type of protocol but I think it's important to you as basic knowledge, maybe theory about also CRC and other checks counting. Hope it helps you go next my friend. https://support.industry.siemens.com/tf/ww/en/posts/siemens-cp340-testing/145907/?page=0&pageSize=10 |
With best regards... |
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This contribution was helpful to1 thankful Users |
3/7/2017 5:49 PM | |
Posts: 49 Rating: (1) |
Hi, I am crazy to asking this question. why we need to calculate LRC??. if LRC value is different mean, how we can figure what kind of error. |
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