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vaggelis

Help with communication protocol

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hi, I am working now with one plc FX3U cpu. I want to build a program with vb.net to read plc data. I found on net the mx component but i don't want right now to use it.I Also found the protocol but i have a question on this.How calculate the address. For example the D123 i found Algorithm Address=address*2 +1000h. i need some example here because the result is 31h,30h,46h,36h but i can't found how calculated. i try to calculate D123*2 decimal values + 1000h to decimal and all to hex but with no result. Thanks

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Hi, FX ASCII protocol is a mixture of octal, decimal, hexadecimal and ASCII. There is also two addressing modes. I have only used the extended mode. When I wrote the driver I made some blocking sheets. This was one part regarding reading data. It should be right. Use PeakHMI in demo mode and issue a read while monitoring the serial port if it does not work for you. The stream from PeakHMI will be correct.

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thanks sparky, It's very usefull the protocol frames do you have an example for data address how to convert it?

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Hello, This is what I have in my notes. Glancing at the source code they look correct.

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Hello, Might I ask, why are you wanting to write something in VB and not use an "off the shelf solution"? School? Learning? Challenge? Nothing off the shelf fits your needs? Cost? Just wondering.

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i am working on ships and we have nitrogen generator with mitsubishi HMI and PLC. With hot ambient temperature this system cannot communicate(hmi with plc) and we alrady had claim about this. I wont to take out the hmi and with my program control the plc. i don't know if i will do it but i will give a try. i don't wont to buy the control because it's expensive and i am not working with mitsubishi plc's and HMI's.

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Hello, Thanks for the answer. >i don't wont to buy the control because it's expensive I assume you are referring to software cost. What do you consider expensive? How much money is too much money, for a HMI software suite?

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Hi Mark, Your thumbnail for read command (E/0x45) was very useful for me. Do you have similar notes for writing to a register (say writing to a Dxxx register)? Thanks Edited by vipresh

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Hello, This might help.

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Thanks Mark. It worked. Just for information, I am developing a web-server so that a Mitsubishi PLC can be accessed thru internet. Both PLC and web-server are packaged in the same cabinet

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