![]() I tried a program online that is supposed to be able to do it but I just keep getting an error every time I run it. When I try to search for a solution online on how to read strings from the plc holding register nothing useful comes up. I got it to read integers from holding register, but not strings. I've done some integration with the Schneider Electric/Modicon platforms and different manufacturers' components, and the biggest issue with that is making sure your registers and bits line up so you know you're reading the correct data.I'm trying to use my raspberry pi as a client for modbus communication between it and a S7-1200 Siemens plc. There is some configuration that must be done up front (AOPs, firmware compatibility, etc.), but after that, I've found the integration of their components to be really intuitive (generally speaking). However, in my experience, you can save a lot of time by integrating different components from the same platform, particularly with Rockwell/Allen Bradley. To answer your second question, anything can be beaten into submission. Depending on your price point, most HMIs will support at least one of these protocols. I would recommend taking advantage of this. I've never used the MicroLogix platform, but from reading the documentation, it looks like there is an on-board Ethernet port that supports Ethernet/IP and ModbusTCP.Įach controller has 2 serial ports with DF1/DH485/Modbus RTU/DNP3/ASCII protocol support and a built-in Ethernet port, which supports EtherNet/IP, Modbus TCP/IP and DNP3 over IP. If you are exchanging a lot of data between the PLC and HMI (real-time rates, status bits, etc.), you might notice a lag in the information being displayed. Without knowing the application, it's hard to say how much it will affect you. ![]() Furthermore, some programming environments support both HMI and PLC so the tags and/or addresses exist together in the same suite. They should definitely know how to get their products talking to one another. What I really mean is that you have one contact for integration support. You only have one person to bitch at when it doesn't work, lol. HMI, I would recommend utilizing Ethernet/IP.Īre there any significant benefits to using the same brand PLC & HMI? protocol which means timing can't really be nailed down. Modbus TCP/IP is a non-deterministic comm. Will you know which one to read from? How? There are multiple register areas inside the memory map which all have different purposes. For instance, if you place a bit at 4x0035d in the PLC it may be referenced by another vendor's HMI at 4x0034d or 4x0036d. Modbus is generally very confusing for beginners because of its register based addressing approach. You lose the ability to explicitly address in logical way. When you move to ModBus, do you lose any functionality? ![]()
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