KROHNE GFC 300 Modbus - Manual (Page 10)

6
MODBUS PROTOCOL
10
GFC 300
www.krohne.com 03/2012 - 7312402100 - AD Modbus GFC 300 R01 en
6.3 Addressing
In the following tables the Modbus protocol addresses / data addresses are listed.
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;
• for Input Registers replace the leading 20 of 20xxx by 9xxx.
Sometimes register numbers are asked for. The register numbers register numbers register numbers register numbers can be calculated by adding a
1 to the protocol address and using a prefix according to the block:
• prefix 1 for coils
• prefix 3 for Input Registers
• prefix 4 for Holding Registers
6.4 Overview of supported functions
The following table shows Modbus functions supported by RS485 interface.
Function code Name Access to
hex dec
01 01 Read Coil Status of calibration functions (not applicable)
Counter status (start/stop)
03 03 Read Holding Register Acyclic Registers
04 04 Read Input Register Cyclic Register
05 05 Write Single Coil Cold start
Warm start
Error reset
Start calibration function (not applicable)
Start / stop counter
08 08 Diagnostics -
10 16 Write Multiple Register Acyclic Registers
2B 43 Encapsulated Interface Transport Transparent Channel
Read Device Identification