leadro venancio da silva Posted June 22, 2017 Report Share Posted June 22, 2017 Hello, I am need help with my application, The controller is USP-104-B10 in may application i am using the Modbus TCP/IP to connect PLC with Scada System... in the computer i am using a software Modbus/OPC when i inserte the fists 255 register everything is ok but more than that i cant read any register Somebody can help me? Quote Link to comment Share on other sites More sharing options...
MVP 2021 Flex727 Posted June 23, 2017 MVP 2021 Report Share Posted June 23, 2017 Do I understand you correctly that you are trying to read 255 registers at once via MODBUS? I believe there is a limit to how many registers you can read with a single Read Holding Registers command (a MODBUS limit, not Unitronics). Try breaking it up into multiple reads. Quote Link to comment Share on other sites More sharing options...
MVP 2021 Joe Tauser Posted July 7, 2017 MVP 2021 Report Share Posted July 7, 2017 Modbus is limited to 125 registers per transfer by definition. Break your table into smaller blocks. Joe T. Quote Link to comment Share on other sites More sharing options...
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