Posted 7 Sep 2023 We are using a Mitsubishi Inverter A800-E series, specifically the FR-A820-00105-E1N6 option, with the built-in Ethernet card. This VFD is connected to a PLC, the Beijer PLC XP-340. For our application we are using two VFDs, each of them connected to the PLC, but that is not relevant for the discussion below. This PLC is on charge of commanding these two VFDs and we have decided to go for modbus for its simplicity, and for the easily available that all the parameters of the VFDs are. We have been able to set up a modbus client in the PLC and read any parameter of the VFD, but we are missing two very basic steps before we can start testing motion: - How can I set up the speed reference of the VFD over modbus? I have gone through the list of parameters one by one, read the list of parameters one by one and I could not find such a parameter. For instance, let’s say I want the motor to move at 1500 rpm. Where can I enter this information to tell the VFD to move the motor at that speed? - How can I tell the VFD ‘go’ or ‘stop’. This is, how can I command it? I have seen something in bits 0-8, but I cannot wrap my head around this. Is this just the We are not familiar at all with PLCs and VFDs, and we are learning as we go, so apologies in advance if the questions above are too basic or if we are missing something very basic (which I think we are). The manuals I have been reading can be found in: - Inverter: https://emea.mitsubishielectric.com/fa/products/drv/inv/fr_a800/fra800e/fr-a820-00105-e1-n6.html#downloads - PLC: https://www.beijerelectronics.com/en/Products/Control___systems/Compact___controller/BCS-XP340#smartengineeringresources Thank you very much in advance! Share this post Link to post Share on other sites
Posted 7 Sep 2023 (edited) Suggest you download and read the ethernet function manual IB(NA)-0600628ENG-B. Understand that by default the drive parameters are set to be controlled by hardwired inputs and outputs and the HIM (human Interface Module). To control via ethernet, you must parameterize the drive to accept control and frequency reference via the ethernet. Unfortunately, I have no experience with Beijer PLCs or any knowledge of their capabilities and communication protocols. I saw a resource regarding comms via Modbus TCP and CANopen. Once the PLC and VFD are talking, then write code to read and write to the VFD. Different platforms use different terminology, but most use what is called implicit or explicit forms to read and write to the VFD. You'll need to determine what the Beijer capabilities are. Maybe find an example code at either Beijer or Mitsubishi to help you. Edited 7 Sep 2023 by pcmccartney1 Share this post Link to post Share on other sites
Posted 7 Sep 2023 5 minutes ago, pcmccartney1 said: Suggest you download and read the ethernet function manual IB(NA)-0600628ENG-B. Understand that by default the drive parameters are set to be controlled by hardwired inputs and outputs and the HIM (human Interface Module). To control via ethernet, you must parameterize the drive to accept control and frequency reference via the ethernet. Unfortunately, I have no experience with Beijer PLCs or any knowledge of their capabilities and communication protocols. I saw a resource regarding comms via Modbus TCP and CANopen. Thank you very much for your response! That is exactly the manual I have been looking at. At the moment I am able to read and write parameters to the VFD via ethernet, but it is the two points above that I am not able to do. I would say the Beijer PLC is not the problem, just a question in the understanding on how the VFD can accept the speed reference and can be set to 'go' or 'stop'. Thanks! Share this post Link to post Share on other sites
Posted 8 Sep 2023 Wow! I perused the inverter manual and the network manual and have decided that the FR-A800 has the lamest Modbus command and status interface I've ever seen--particularly the use of specific modbus registers with different meanings for read and write. There's no way to find out the last instruction sent to such a register. The parameters for control source selection are also almost unbearably complex (in the manual, §5-9-1 through §5-9-3). There's no way I'd ever recommend this drive to any of my clients. 1 person likes this Share this post Link to post Share on other sites
Posted 8 Sep 2023 Just now, pturmel said: Wow! I perused the inverter manual and the network manual and have decided that the FR-A800 has the lamest Modbus command and status interface I've ever seen--particularly the use of specific modbus registers with different meanings for read and write. There's no way to find out the last instruction sent to such a register. The parameters for control source selection are also almost unbearably complex (in the manual, §5-9-1 through §5-9-3). There's no way I'd ever recommend this drive to any of my clients. I know... but sadly we are stuck with this option :( Share this post Link to post Share on other sites
Posted 8 Sep 2023 58 minutes ago, pturmel said: particularly the use of specific modbus registers with different meanings for read and write. Yes very strange having the same register as the control / status Share this post Link to post Share on other sites
Posted 8 Sep 2023 We use quite a few Mitsubishi drives, however we only control the speed via Modbus TCP as the run is done through a relay (the electrical designer prefers this as he likes to link it in with a safety circuit). To control the speed we simply write to the min speed parameter no 2. Been doing this for several years without a problem. Share this post Link to post Share on other sites
Posted 8 Sep 2023 9 hours ago, pturmel said: Wow! I perused the inverter manual and the network manual and have decided that the FR-A800 has the lamest Modbus command and status interface I've ever seen--particularly the use of specific modbus registers with different meanings for read and write. There's no way to find out the last instruction sent to such a register. The parameters for control source selection are also almost unbearably complex (in the manual, §5-9-1 through §5-9-3). There's no way I'd ever recommend this drive to any of my clients. It look like you have not used it. From my experience, if you want job done it is the best ever VFD I have used (and I have used many different VFDs from various producers). Just to mention that PLC function inside it has, that is very powerful. I have used it for several application where servo was originally intended . Only drawback is the price. Maybe my language barrier is making problem to me, but I don't understand what are the problems you noted with frequency/speed reference. You can program it to have three control modes that are selectable either from VFD or through communication, and every mode can work in different way. I think that it is benefit not drawback. Share this post Link to post Share on other sites
Posted 8 Sep 2023 1 hour ago, Goran Vuckovic said: It look like you have not used it. Correct. You may be right about everything else it offers. But it definitely has a lame Modbus implementation. If the only practical common protocol between the PLC and the drive is Modbus, then I consider this drive absolutely unacceptable. Share this post Link to post Share on other sites
Posted 8 Sep 2023 42 minutes ago, pturmel said: If the only practical common protocol between the PLC and the drive is Modbus, then I consider this drive absolutely unacceptable. It has Modbus, CC-Link (all versions, Serial&Ethernet, IE, TSN), Profinet, Ethernet/IP, Mitsubishi Inverter Protocol, Profibus, Devicenet, CANopen, Controlnet, FL-Net, Lonworks, BACnet, SSCNet, EtherCAT. Some of them are standard, and some of them are as option. So Modbus is far from only protocol. About Modbus implementation, I am not 100% sure if it has Modbus FC23 Read/Write, but other than that I don't see how it is lame. There is one thing with Mitsubishi VFDs and that is that Parameters Number are practically always the same in last cca 35 years, on every model Mitsubishi is adding parameters not changing them, so you don't need to learn it again, but it tends to be confusing for new guys. As remedy there is FR Configurator Software that helps a lot. Share this post Link to post Share on other sites
Posted 8 Sep 2023 4 hours ago, Goran Vuckovic said: It look like you have not used it. From my experience, if you want job done it is the best ever VFD I have used (and I have used many different VFDs from various producers). Just to mention that PLC function inside it has, that is very powerful. I have used it for several application where servo was originally intended . Only drawback is the price. Maybe my language barrier is making problem to me, but I don't understand what are the problems you noted with frequency/speed reference. You can program it to have three control modes that are selectable either from VFD or through communication, and every mode can work in different way. I think that it is benefit not drawback. The problem that I am facing is that I cannot write to those registers. I can read from them, but whenever I try to write to the register I get the exception Invalid value. (no matter what value I try to give to it) Share this post Link to post Share on other sites
Posted 8 Sep 2023 5 hours ago, Goran Vuckovic said: I don't see how it is lame. You can't read back the control word or reference after writing. (FC23 has no significance for that flaw.) If you don't think that is lame, we'll have to disagree. Share this post Link to post Share on other sites
