Thytronic NA60-MB0 PRON Series - 1.4 Supported functions; 1.5 Exceptions

PRON NA60-MB0
Version 3.50
PRON NA60-MB0 Remote Setting Manual Page: 4 of 59
1.4 Supported functions
TPR supports the following Modbus functions:
Code Name
0x01
0x02
0x03
0x04
0x05
0x06
0x0F
0x10
Read Coil Status
Read Input Status
Read Holding Registers
Read Input Registers
Force Single Coil
Preset Single Register
Force Multiple Coil
Preset Multiple Registers
Table 3 Supported Modbus functions
The smallest data that can be exchanged within a Modbus message is the Modbus Register.
A Modbus Register is a 16 bit data in the Big Endian representation, called WORD (W)
W = B
H
B
L
1.5 Exceptions
When a TPR receives a request that can not handle (e.g. the data address doesn’t exists, the function is not
supported, etc.), a special response called Exception is returned to the Master. This message contains the
information needed to recognize the error occurred.
In an Exception message the most significant bit (msb) of the Function field is set to 1.
• Function Code field: in case of exception, the msb is set to 1.
• Data field: this field contains a value related to the kind of error generated by the request.
An example of request with exception response could be the following:
04 07 A5 50 00 02 - -
TX
S F ADR DIM CRC
04 87 01 - -
RX
S F DATA CRC
S = Slave Address
F = Function Code
ADR = Modbus Data Address
DIM = Dimension (number of registers)
DATA = data value
CRC = Cyclical Redundancy Code
In this example the function code 07 is not supported by the TPR. The response is an exception message (the msb
of function code F=0x87 is set to 1). The Data field value is 1 and according with the Modbus standard corresponds
to the “Illegal function” exception.