UniData Communication Systems 6527B, Руководство пользователя

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Manual – Starflow QSD Model 6527B and 6537A
Unidata Manual - 6527B and 6537A Starflow QSD User Manual 17 01 2020.docx Page 13
4.2.2 Master Format
Device Address Function Code Data Payload CRC
Device address – 1 byte field ranging from 1 to 247. Broadcast address 0
Function code – 1 byte field with a value range 1-127 representing the standard or extended
function code
Data payload – 0-N bytes with response data from the device. Error response will be a 1 byte
value 1-255.
CRC – 2 bytes computed mathematically
4.2.3 Slave Response Format
Device Address Function Code Data Payload CRC
Device Address – Echo of device address sent in master message to the device
Function code – Echo of function code sent in master message to the device
Data payload – 0-N bytes with response from device.
CRC- 2 bytes with a value computed mathematically
4.2.4 Standard Message Format
Read Holding Registers is used to retrieve measurements
Message Response
Address 1 byte 1-247 Address 1 byte 1-247
Function Code 1 byte 0x03 Function Code 1 byte 0x03
Data Address 2 bytes 0 to 0xFFFF Byte Count 1 byte
Register Count 2 bytes Data Payload N bytes
CRC 2 bytes CRC 2 bytes
*Byte count = 2*Register Count
Write Single Register is used to configure instrument settings
To set a single register in a device:
Message Response
Address 1 byte 1-247 Address 1 byte 1-247
Function Code 1 byte 0x06 Function Code 1 byte 0x06
Data Address 2 bytes 0 to 0xFFFF Byte Count 1 byte 0 to 0xFFFF
Register Count 2 bytes 0 to 0xFFFF Data Payload N bytes 0 to 0xFFFF
CRC 2 bytes CRC 2 bytes