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| 8/30/2016 1:45 PM | |
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Posts: 10 Rating:
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Hello, We have a CM PtP : 6ES7 137-6AA00-0BA0, set as a modbus RTU master on a 2 wire RS485 bus. We have to read read and write data to 28 temperature controllers and drives and energy meters. i have done the programming and quite successful with the communication with the devices. i have no problems reading data. for e.g. MODBUS Register 40018 40018 Parameter MBID Description Modbus ID Format Unsigned 16 bits R/W Units NA i'm able to read data from Unsigned 32 bits R/W registers also. Howeve, the difficulty i face is with this. MODBUS Register 40001 40004 Parameter SrNLo Description Meter Serial Number Format ASCII (8 bytes) Units NA Remarks Meter Name The Format specified for this register is ASCII (8 bytes) and, I tried various combinations of declaring the target address in the S7 data block. namely, array of 4 words, array of 8 bytes and one double. accordingly, i changed the "DATA_LEN" in the "MODBUS_MASTER" block, again various combinations with 8 / 4 / 1. clearly it's a mistake, as i understand that by modbus standards, it's only bits/bool and words. all the other data types are scaled or fitted into "words" type registers. I need help with accessing ASCII (8 bytes) of data and to know how to declare the proper data type in the S7 data block, and the length to be specified in "DATA_LEN" in the "MODBUS_MASTER" block. The engineering software i use is TIA Portal V13. Regards, Kiru...! Attachmentforum 20160830_1636.zip (101 Downloads) |
| 8/31/2016 7:37 AM | |
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Posts: 10 Rating:
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Hello Smiffy, Thanks for the fast response. I did try as you said... I get error code 818D or 8393.. Any other possibilities to try? |
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