Functions; Reading N Words; Writing One Word - JUMO IPC 300 Operating Manual

3

Functions

The following functions are available for the device:
Function number
0x03 or 0x04
0x06
0x10
If the device receives an instruction with a different function number, it will respond with the Modbus error
code 1 (ILLEGAL FUNCTION) in this case.
3.1

Reading n words

This function is used to read n words starting at a specific address.
Data request
Slave address
1 byte
Response
Slave address
1 byte
Example
Reading the measured value for the load current
Modbus address of the load current = 0x00B1
Data request:
01
Response:
01
3.2

Writing one word

The data blocks for the instruction and response are identical when writing a word.
Instruction
Slave address
1 byte
Response
Slave address
1 byte
Function
Reading n words
Writing one word
Writing n words
Function
0x03 or 0x04
1 byte
Function
0x03 or 0x04
1 byte
03 00
03 04
Function
0x06
1 byte
Function
0x06
1 byte
Address
First word
2 bytes
Number
Number of bytes
read
1 byte
B1 00
70 A3
Load current = 12.24 A
Word address
2 bytes
Word address
2 bytes
3 Functions
Maximum number
Max. 127 words (= 254 bytes)
1 word
Max. 127 words (= 254 bytes)
Number of words Checksum
(max. 127) CRC16
2 bytes 2 bytes
Word value(s) Checksum
CRC16
x bytes 2 bytes
02
41 45
Word value Checksum
CRC16
2 bytes 2 bytes
Word value Checksum
CRC16
2 bytes 2 bytes
942C
E172
CRC
13