86INM 725B Rev 2113 4 2 Modbus Slave – Entry LevelFunction DescriptionsThis section describes the process of reading from and writing data to a RTK 725B slaveannunciatorRead Coil Status – Function 01 – RequestRegister AddressThis is used to address the “start” channel to be read for example the first channel in thesystem “channel 1” would be register address 00 00To read the input read coils 0-3To read the remote pushbutton inputs on the card read coils 4-6Number of RegistersThis represents the number of coils, (Inputs), the user wishes to read. This can be 1-7 coils.13 4 3 Read Coil Status – Function 01 – ResponseByte CountThis represents the number of bytes sentDataThis represents the status of the requested channelInput0 = Input Normal1 = Input AbnormalTypical Example of Message FormatTo read all of the inputs available on the first alarm card in the system the user would need toread 4 digital and 3 remote pushbutton inputs using the following message formatADDRESS FUNCTION REGISTER ADDRESS No. of REGISTERS ERROR CHECK01 01 00 00 00 07 7D C8To read channel two on the second alarm card in the system you would need the followingmessage formatADDRESS FUNCTION REGISTER ADDRESS No. of REGISTERS ERROR CHECK02 01 00 01 00 01 AC 39
