Damian91 Posted October 27, 2019 Report Share Posted October 27, 2019 Hello we have a problem with communication with Modbus slave V570. SCADA (as a master) send request READ HOLDING REGISTERS and READ COILS to slave. Function READ HOLDING REGISTERS works fine. SCADA read registers MI, but function read coils doesn't work. SCADA cannot read registers MB. I checked also the system bits SB305, and it is false. Quote Link to comment Share on other sites More sharing options...
MVP 2021 Joe Tauser Posted October 28, 2019 MVP 2021 Report Share Posted October 28, 2019 I don't know what SB 305 is. Where did you get that? As far as reading coils, do you know if your SCADA system is issuing function 01? What address are you giving it? Joe T. Quote Link to comment Share on other sites More sharing options...
AlexUT Posted October 28, 2019 Report Share Posted October 28, 2019 Hi Joe See following MODBUS topic: ModBus address access limitationhttp://forum.unitronics.com/topic/6641-modbus-address-access-limitation/ It explains SB305 B.R. Quote Link to comment Share on other sites More sharing options...
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