3/12/2024 0 Comments Modbus address hmi register![]() So, please tell me I'm wrong and tell how can SBs and Inputs via Modbus from a Unitronics OPlc. I guess there should be a way to read inputs, since there is a "Read Input" function block in Visilogic Modbus Master. There is offcourse the chance to "map" SBs or Inputs to MBs and then read them as MBs, but is not a clean way to do it, and you need to consume MBs just for mapping purposes. Modbus offcourse supports 1xxxx addresses for inputs, but Unitronics OPLCS seem to support only 0xxxx (coils) and 4xxxx (registers). Well, this simply doesn't work, reading addresses 3000 or 4000 does not return SBs or Inputs, also any attemp to read a coil address above 4095 will return an error. (similar story for registers different from MIs) In the Modbus Read Holding registers, this is where you define the Server(Slave) address to read from.- Trim the program to work with 1 Modbus Slave unit to start, and get it working, then add the others in. Or in order to read OPLC discrete inputs you should read coils starting at 4000 You have to set up each device to a different Modbus Address. This table apparently indicates for example that in order to read SBs you should read coils starting at 3000 address Visilogic help shows a "slave adressing" table. I've been able to read and write MIs and MB successfully.īut I'm not able to access any other type of addresses. ![]() I've implemented Modbus communications with Unitronics Vision series, both serial and Ethernet.
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