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Hi, I hope you might help with the following issue: I wrote a simple python library, using the PCOM protcol & pySerial. To test it, I created a script that reads a few Memory Bit operands from a SM-43 via the built-in RS232-USB Bridge. The library and the script work perfectly, accept when it comes to reading more than seven bit operands: I used the online mode to set the MB100-107 to the values : 10101100. While the response comes back intact, ( checksum checks out etc) I'm getting different responses for the same request. The respective bytes in the payload of the response message vary between: 0x3521 0x3523 0x3544 0x3543 0x35cb Note that I made sure that the actual bit values in MB100-107 do not change The response is consistent, as long as I don't change the status of MB107. However, as soon as I'm toggling MB107 on and off again, i get a different response from the PLC afterwards. I also get a different response when I change the read request and then go back to the old read request. The first seven bits do not seem to be affected by this - They show 0x35 consistently. Maybe I overlooked something? Thanks in advance for any hint! Max
Hello all, I have an 11 bit absolute rotary encoder that outputs in gray code. Here is datasheet on it: https://cdn.automationdirect.com/static/specs/encodermda.pdf This is needed for determining the position of the shaft on an engine. I am fairly new to Unitronics and Visilogic. I have a V700 with the V200-18-E3XB snap on. I have looked at other answers on this topic and have created a ladder diagram based on this format: http://www.plcdev.com/using_ladder_logic_for_gray_code_conversion However, I am still stuck when it comes to getting the binary to decimal and then being able to read the position output from the encoder on the HMI. I am a college student working on my senior capstone. Any and all help is appreciated. Thanks, Robby
I'm trying to write values and I'm not sure what the binary WRITE message format is, in relation to the READ message format. I couldn't find this answered in the PDF or on the forums yet. I read a summary in the PDF that byte 12 should be changed to 68 and the write values should be appended to byte 32 (which confused me further as that's after the footer checksum). This is what I have for READ: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | 24 25 26 27 28 29 | 30 31 32 stx-------------- id FE 01 00 00 00 cn 00 specific--------- lengt chksm | numbr ot FF addr- | chksm ex What would be the correct format for WRITE?