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    • By Abel_Souza
      LabVIEW 2016
      Modbus Communication with a PLC Siemens SIMATIC ET 200SP
      Windows 7 Ultimate
       
      Hi,
       
      When I run my code it return error 66 at Read Holding Registers function. I ran this code as a VI on the development virtual machine and as a *.exe on real machine, but received the same error.
      Try in another computer and receive the same error.
      As PLC code was developer by other programmer I ask him if this communication was working on his machine, he showed me a LAbVIEW code running with Modbus communication with the same PLC. He was using a LabVIEW 2013 with old Modbus Library, but I had taken his code and ran on my PC with LV 2016 and receive the same error on MB Ethernet MAster Query Read Holding Registers(Poly).vi. Also generate an exe file and run on my real machine and still receiving error 66.
      In all scenarios I can ping PLC and receive answers, but cannot read or write any data with LabVIEW.
       
      First picture is my code with LV 2016 VIs.
      Second picture is error message.
      Third one is the other programmer code with old Modbus Library.
       

       
      On the first code, if I remove Read Holding Registers VI and connct wires directly or put a property node to set any property it runs without errors. If change this function for any other modbus function return error 66.
       
      Any idea what I am doing wrong?
       
      Thanks in advance!
      ni_support.zip
      Comunicação CLP.vi
      Main_MB_2.vi
    • By dterry
      Hello all,
      I recently was presented with the task of integrating a Mitsubishi PLC into our systems. After a good deal of googling, I think the best (maybe only) way to get the data out is going to be via OPC, thanks to their proprietary Melsoft protocol. If anyone else knows a better way, feel free to stop me here.
      Now, we are currently expanding our data generating capabilities (hence the PLC), and I have been thinking about rearchitecting the way we collect data from all over our facility to be more flexible.  Since I may be required to use OPC anyways, I was considering using an OPC server to aggregate all of the facility data, and then redistribute to control rooms, historical logging, etc.  To do this, we would need to integrate our cRIOs and operator PCs into the OPC environment as well.
      I don’t see OPC mentioned very often (in fact it returns 0 results on LAVAG), and a lot of the stuff I see these days seems to be more “roll your own” or lower level (raw TCP/UDP, 0MQ, Network Streams, Transport.lvlib etc.) rather than a monolithic abstracting bridge like OPC. Unfortunately, I won’t have time to roll my own in the near future, but LVRT supports supports OPC UA, so I could potentially integrate the cRIOs fairly easily.  Unfortunately, I think I would have to use LabVIEW DSC (or datasockets...) to integrate the PCs.
      I would be very grateful if anyone has the experience to comment on the following or anything else related to using OPC.
      What are viable update rates for OPC tags?  I will need at the very (very) least 250 ms update rates.  Is OPC typically low latency (time from data generated to to client received)? Does anyone have a recommendation for a product (NI OPC, Kepware, etc.)? Is OPC still popular, or are there other options for data aggregation that would be better suited to a new application? What are the options for logging and alarming with OPC? What are the options for talking to OPC from LabVIEW? How robust are the OPC connections in regards to reconnecting if a wireless connection is temporarily lost? Thanks in advance!
    • By Ricardo de Abreu
      Hi Guys, I'm with a trouble here.
       
      Recently we started to get our outdated temperature test cabinet to work, and the best way is to upgrade our PLC. But there cames 2 problems, the biggest is the budget, we do not have any money so we have to work with what we already have, and the second, i'm intern here and there is no one from automation to guide or help me.
       
      Now lets face the problem.
       
      PLC Allen Bradley micrologix 1100
      cards: 1762-IQ16 and 1762-IQ8W6
       
      My first thought is to use Labview to control the PLC, as HMI and data-logger without OPC server to simplify the instalation and cost.
       
      The communication: this is really where the problems begin. It will be done through Ethernet. I could not manage Ethernet/IP driver to work, nor pcc or CIP message...
       
      which is the best way to communicate?
      CIP Message, OPC, or any other i do not know? Do you guys see any problems to make a dataloger without OPC?
       
      Some things I have tryed
       
      Implementation of Common industrial Protocol (CIP) via EtherNet [EtherNet/IP (CIP)]
      https://lavag.org/topic/6104-industrial-ethernet-ethernetip/?page=1
       
      Ethernet/IP Driver for Micrologix 1100
      https://decibel.ni.com/content/docs/DOC-13024
       
      EtherNet/IP Driver for Industrial Communication
      https://decibel.ni.com/content/docs/DOC-4065
       
       
      Thanks for any help
      Ricardo
      PS. Originally posted at: https://decibel.ni.com/content/thread/47497
    • By Ricardo de Abreu
      Hi Guys, I'm with a trouble here.
       
      Recently we started to get our outdated temperature test cabinet to work, and the best way is to upgrade our PLC. But there cames 2 problems, the biggest is the budget, we do not have any money so we have to work with what we already have, and the second, i'm intern here and there is no one from automation to guide or help me.
       
      Now lets face the problem.
       
      PLC Allen Bradley micrologix 1100
      cards: 1762-IQ16 and 1762-IQ8W6
       
      My first thought is to use Labview to control the PLC, as HMI and data-logger without OPC server to simplify the instalation and cost.
       
      The communication: this is really where the problems begin. It will be done through Ethernet. I could not manage Ethernet/IP driver to work, nor pcc or CIP message...
       
      which is the best way to communicate?
      CIP Message, OPC, or any other i do not know? Do you guys see any problems to make a dataloger without OPC?
       
      Some things I have tryed
       
      Implementation of Common industrial Protocol (CIP) via EtherNet [EtherNet/IP (CIP)]
      https://lavag.org/topic/6104-industrial-ethernet-ethernetip/?page=1
       
      Ethernet/IP Driver for Micrologix 1100
      https://decibel.ni.com/content/docs/DOC-13024
       
      EtherNet/IP Driver for Industrial Communication
      https://decibel.ni.com/content/docs/DOC-4065
       
       
      Thanks for any help
      Ricardo
      PS. Originally posted at: https://decibel.ni.com/content/thread/47497
    • By FJ_Sanchez
      Hello,
       
      I've been using Snap7 library for a while in the client role, so I can communicate with SIEMENS PLCs There is specific LabVIEW info here: http://snap7.sourceforge.net/labview.html
      I can successfully use the Cli VIs to read/write from PLCs DBs (a DB is just a memory block). For reading I pre-allocate a buffer, but I'm not sure if I'm doing it properly. My main concern is about memory leakage, I don't know if the memory will be freed after the VI exits or it will not be freed as long as the VI is in memory.
       
      Attached is what I have just now for reading. I define a typedef for each DB, it is a cluster of booleans, and reserve memory according to the number of booleans, but always in multiple of 8 (I read only bytes). I request the data with the CliDBRead and after that I make some conversions to return the data in a variant that I later cast to the proper typedef.
       
      Can you tell me if this is the best way to do this?
       
      Thank you!

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