KROHNE MFC 400 Modbus - Manual (Page 11)

MODBUS PROTOCOL
5
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MFC 400
www.krohne.com 05/2013 - 4002525102 - AD Modbus MFC 400 R02 en
5.3 Modbus Register Addresses
The signal converter supports four types of data references, which are associated to a range of
Modbus registers.
5.4 Supported Function Codes
For detailed information about the telegrams structure of all function codes refer to Supported
Modbus function codes on page 33.
5.5 Error messages
When the signal converter detects an error in the requests, received in a properly formatted
telegram, it will respond with an error message. The error message response telegram is
formatted as follows:
The msb (most significant bit) of the requested function code is set (add 0d128 / 0x80) in the
reponse telegram to indicate an error has been detected. For example, if an error were detected
in a function 1 request, then the returned function code would be 0x81 (0d129).
Address range Primary tables Access rights
0...9999 Coils read + write
10000...19999 Discrete Inputs read
20000...39999 Input Registers read
40000...65535 Holding Registers read + write
INFORMATION!
• Sometimes register numbers are asked for. The register numbers can be calculated by
adding a 1 to the register address.
• Some systems cannot use addresses above 9999. For these systems there is the possibility to
use the listed addresses but
- for Input Registers omit the leading 3 of 3xxxx;
- for Holding Registers omit the leading 4 of 4xxxx.
Function code Name
dec hex
01 01 Read Single Coil
02 02 Read Descrete Inputs
03 03 Read Holding Register
04 04 Read Input Register
05 05 Write Single Coil
08 08 Diagnostics
16 10 Write Multiple Register
43 2B Encapsulated Interface Transport
Address Function Code Error Code CRC Lo CRC Hi