Lupin_III

HI, I'm reading values from an SBC SAIA PLC ( PCD2.M5540 model). My problem is that some values are 32 bit, while modbus return 16 bit values, of course. Registers are consecutive, so I cannot read for example 9008 and 9009 since they store 2 different information.To make it clearer I attach the PLC watch window. As you can see R9009 is a 32 bit value, but I can't require R9009 and R9010 via modbus since in R9010 register there is a different information. AS well as in R9008. Speaking with SAIA technical support, they explain me that their PLC registers are natively 32 bit, so in order to read them I need a 32bit modbus client. I cannot find anything like this, neither I can use standard modbus, since the buffer I get back is a 16 bit for each register. So 16bit for R9008, 16bit for R9009, 16 bit for R9010. What I can do?Thanks

Thanks Mark. I had a look at it. The problem is that I neeed to integrate it in another program. This will leead to a dedicate saolution just for this PLC. So, I need to use standard modbus.

Thanks. After more research it seems that I have to find which register these are are linked to, the standard one that allow modbus protocol. So now I need someone that knows this PLC. 

Thanks Bob

Hi, I have an FX3U PLC with an FX3U-232ADP-MB. I'm able to correctly receive data from PLC with the RS2 instruction (the PLC every 5 minutes automatically sends a string by mean of this instruction). My problem is when I try to write data. Practically the PLC wait for receiving 2 identical messages within 20 seconds. As soon as it receives the first message, this is temporarily stored in a different buffer. Within 20 seconds when it receives the second ones, the two are compared and if they match you can go ahead sending the messages in order to write data. My problem is that this2 messages doesn't match (even if they are of course the same). Being connected to the PLC I can read the data directly inside the registers, and I cannot understand why. Even the first message received from the PLC is different. I don't think the problem is the connection, otherwise I should even received wrong data. Moreover, for the two messages I send, always the same bytes are different.

Hi Gambit, it helps me a lot, the problem was the cable. Everything works great now. Thanks so much for the support 

Thanks, I'll try and share the results as soon as possible

Thanks Gambit. Unfortunately I can't successes in it. I 'don't find any further useful info within the manual and I tried everything that came to mind, including with and without STX (02H) and ETX (03H)  inside ed outside the string length declared. I even tryed to send the string directly in bytearray, but nothing. It's always the same. I've called Mitsubishi support, looking together the program, but unfortunately they weren't able to help me, either. The area within the RS2 instruction it's written only from this instruction itself. They think the problem is that somehow the program I use to send the string (python under raspberry) add some characters.I don't think so, I even tried some other tool on PC Win 10 and the result is exactly the same. Can you suggest me some tool that I can use in order to see what goes through the serial port, what code really leave my computer?

Thanks for your time Gambit. No, I'm not using STX and ETX characters (actually I'm not that expert on this but no, I don't think I'm using these characters). I'm not in front at the PLC at moment so I go by heart with the following example. This is the string I send: "{2@1111111|I000   }" and what I see inside the PLC registers is something like this: "{1@1111111H000   }" or "{1@1111111|H000   }" or "%@1111111H000   }" I tried to attach the imagine with the CH settings, but I don't know why there is always a problem uploading it. Anywhay: Protocol: Non-Procedural Data Length: 8Bit Parity: None Stop Bit: 1Bit Transmission Speed: 38400 Header / Terminator / Control Line / Sum Check: disabled H/W Type: Regular /RS-232C Control Mode:Invalid Transmission Control Procedure: Form1(Without CR,LF) Station Number Setting: 00H Time Out Judge Time: 1x10ms

I'll have a look at it more in details. Do you know it? Could you give me an hand? For what I understand this is a good way for creating a new interface, and for sure I'll study it in deep At this real moment , I need a more faster solution (faster for me of course). Once a did the same with a Siemens S71200, using python and Snap7. So, in a really simple way once connected to the PLC I can read the data I need, knowing its address. And this is the same I would like to do now with this Mitsubishi.

Hi, I need to connect an FX3U Mitsubishi PLC with my raspberry for reading some data and put them into a charts. I was thing on using python but I'm not finding much help on how to do it. The PLC is even connected with an HMI GT1050-QBBD. I really appreaciate every kind of help you can give me. Thanks to all

Hi, I see that are passed quite a few years, but I still don't find much help on this topic and I need help to connect a PLC FX3U to a Raspberry using python. Can you help me? Thanks