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Modbus Node Scan
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I've got a couple of Modbus/tcp devices on the network, but the 'node scan' doesn't see anything when pointed at the correct IP address. Does anyone know what the 'node scan' is attempting to do/ how it works? (I need to work out if it's not working because the devices don't support the 'scan' request, or if there is some other problem)
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Hi ChargeRegulator, welcome to the forum!
The Modbus scan tool is going through the slave IDs from 0 to 240 one at a time sending read holding registers at offset zero for one register: https://github.com/infiniteautomation/modbus4j/blob/master/Modbus4J/src/com/serotonin/modbus4j/ModbusMaster.java#L185
It will use the retry and timeout settings from the data source configuration, so if you are hoping it will discover a slave with a high slave ID, it may be many minutes before it even tries that ID.
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OK, got the device set up correctly and the node scan finds it now! On to the next step..
