User Manual For - CONTROLLER/DATA RECORDER MultiCon CMC-99/141
integer part of the value contained in float registers and multiplied by 10 (e.g.: float is 1.2345, D.P. = 0.0, then Integer = 12).
Similarly when decimal pint is 0.000 then integer represents integer part of the value contained in float registers and
multiplied by 1000 (e.g.: float is 1.2345, D.P = 0.0, then Integer = 1234)
Tab. 7.9 List of register available in the device
7.15.2.5.
Modbus SLAVE - Transmission errors handling
If an error occurs during reading or writing one of the registries, then the unit shall return
the frame containing the error code (according to the Modbus protocol).
Error codes should be interpreted as follows:
01h
- illegal function (only functions 03h, 04h, 06h and 10h are available),
02h
- illegal register address
03h
- illegal data value
7.15.2.6.
Modbus SLAVE- Example of query/answer frames
The examples concern a unit with address 1. All the values are given in the hexadecimal
system.
Designations:
ADDR
Address of the device in the system
FUNC
Function number
REG H,L
Higher and lower part of registry number the command refers to,
COUNT H,L
Higher and lower part of registry counter number the command refers to,
starting with the register which is defined by REG (max. 32)
BYTE C
Number of higher bytes in the frame
DATA H,L
Higher and lower part of data word
CRC L,H
Higher and lower part of CRC sum
1. Read of ID code
ADDR FUNC
REG H,L
COUNT H,L
CRC L,H
01
03
00
21
00
01
D4
00
The answer:
ADDR
FUNC
BYTE C
DATA H,L
CRC L,H
01
03
02
DATA H,L - identification code (2060h)
2.
Read of the registers 401h, 402h and 403h in one message (example of reading a number
of registries in one frame):
ADDR FUNC
REG H,L
COUNT H,L
CRC L,H
01
03
04
01
00
03
55
3B
COUNT L - the count of registers being read (max. 32)
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