WAGO-I/O-SYSTEM 750 Process Image 61750-644 Bluetooth® RF-TransceiverManualVersion 2.0.0, valid from FW/HW Version 03/03Table 36: Status byte SStatus byte SBit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 01 0 REG_NOREG_NO Register number (e.g. 56 or 57)All register communication processes follow the request/response principle:1. A request is made in the output process image (PIO). This can be generatedby a PLC application, for example.2. The I/O module generates a response in the input process image (PII).There is a request when the value of REG_NO or RW changes in the PIOcompared to the previous status or register communication is remapped. If writeaccess is involved, the I/O module also processes bytes D0 and D1 of the PIO asnew values for register REG_NO.There is a response when the value of REG_NO or D0 or D1 changes in the PIIcompared to the previous status. If it involves read access in the previous request,the D0 and D1 bytes then receive the current value of the REG_NO register.6.3.4 Parameter ChannelSome I/O modules of the 750 series offer a protocol subsequently referred to as“parameter channel” for the configuration. Parameter channel provides readand/or write access to up to 256 parameters, i.e. data words of the respective I/Omodule. The protocol allows, for example, data exchange between the 750-644I/O module and a PLC application.The parameter channel uses register communication to transport data:• Register 56: Parameter data is stored here word by word.• Register 57: Communication is controlled for the data.The basic sequence for reading a parameter is:1. Write register 57 with the read request command.2. Read register 57 to check the execution status.3. If the read request was successful: Read register 56 to obtain the requesteddata.
