Tempco TEC-9300 - Chapter 9 Modbus Communications; Functions Supported

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Chapter 9 Modbus Communications
Function 03: Read Holding Registers
Query: (from Master) Response: (from Slave)
Slave address (0-255)
Function code (3)
Starting address of register Hi (0) Byte count
Starting address of register Lo Data 1 Hi
(0-79, 128-131) Data 1 Lo
No. of words Hi (0) Data 2 Hi
No. of words Lo (1-79) Data 2 Lo
CRC16 Hi •
CRC16 Lo •
•
•
•
CRC16 Hi
CRC16 Lo
Function 06: Preset Single Register
Query: (from Master) Response: (from slave)
Slave address (0-255)
Function code (6)
Register address Hi (0)
Register address Lo (0-79, 128-131)
Data Hi
Data Lo
CRC16 Hi
CRC16 Lo
Function 16: Preset Multiple Registers
Query: ( from master ) Response: (from slave)
Slave address (0-255)
Function code (16)
Starting address of register Hi (0)
Starting address of register Lo (0-79, 128-131)
No. of words Hi (0)
No. of words Lo (1-79)
Byte count (2-158) CRC16 Hi
Data 1 Hi CRC16 Lo
Data 1 Lo
Data 2 Hi
Data 2 Lo
•
•
•
•
•
CRC16 Hi
CRC16 Lo
This chapter specifies the Modbus Communications protocol as RS-232 or RS-485 interface module
is installed. Only RTU mode is supported. Data is transmitted as eight-bit binary bytes with 1 start
bit, 1 stop bit and optional parity checking (None, Even or Odd). Baud rate may be set to 2400, 4800,
9600, 14400, 19200, 28800 and 38400.
9-1 Functions Supported
Only function 03, 06 and 16 are available for this series of controllers. The message formats for each
function are described as follows: