ZT372a-E GJR2237800R1 HE663909-31828 module

How to Use the Byte Count Field: When you construct responses in buffers, use a Byte Count value that equals the count of 8-bit bytes in your message data. The value is exclusive of all other field contents, including the Byte Count field. Figure B-4 ‘Slave Response with RTU Framing’ shows how the byte count field is implemented in a typical response.The NMBA-01 supports three Modbus function codes. These allow the Master to read and write 16-bit integer values to the drive. 03 Read Holding Registers Reads the binary contents of holding registers (4X references) in the slave. Broadcast is not supported. Query The query message specifies the starting register and quantity of registers to be read. Registers are addressed starting at zero: registers 1– 16 are addressed as 0–15.

Response

 The register data in the response message are packed as two bytes per register, with the binary contents right justified within each byte. For each register, the first byte contains the high order bits and the second contains the low order bits. Data is scanned in the slave at the rate of 125 registers per scan for 984-X8X controllers (984–685, etc.), and at the rate of 32 registers per scan for all other controllers. The response is returned when the data is completely assembled.The contents of register 40108 are shown as the two byte values of 02 2B hex, or 555 decimal. The contents of registers 40109–40110 are 00 00 and 00 64 hex, or 0 and 100 decimal.

06 Preset Single Register 

Presets a value into a single holding register (4X reference). When broadcast, the function presets the same register reference in all attached slaves. Query The query message specifies the register reference to be preset. Registers are addressed starting at zero: register 1 is addressed as 0. The requested preset value is specified in the query data field. The NMBA-01 uses 16-bit values.