Modbus Functions; Function Codes; Exception Codes - Hanna Instruments HI520 Instruction Manual

15
6. At the end of the process, use function code Write Single Holding register (06) to set B3 in
Register.
` A successfully sent command is followed by the controller entering Remote Save mode. A parameters
working image is stored to the controller's non‑volatile memory. During this time the controller enters
the Hold Mode and the new values are stored. Subsequently, the controller runs an Init process to
reload new values.
7. Use function code Read Holding register (03) to confirm B2 and B3 have been cleared from
Register during the Remote Save process.
` This confirms the controller has exited Remote Editing mode.

5. MODBUS FUNCTIONS

HI520 controller's parameters can be read or modified via Modbus functions.
Parameters are grouped based on their functionality. Not all addresses are used; unused addresses are not shown.

5.1. FUNCTION CODES

The HI520 supports the following standard Modbus function codes:
Decimal
1
2
3
4
5
6
15
16
• Read‑only parameters can be reached via Read Input (02) and Read Input Register (03) functions.
• Read & write parameters (and settings) can be accessed using:
A. coil functions
` Read Coil (01), Write Single Coil (05), and Write Multiple Coils (15)
B. holding register functions
` Read Holding Registers (03), Write single Holding register (06) and Write multiple Holding registers (16).

5.2. EXCEPTION CODES

Standard Modbus exception codes are returned by
Code Name
01 Illegal function
02 Illegal data address Received data address can not be accessed by the controller.
03 Illegal data value
04 Server device failure An error occurred while the controller was attempting to perform requested action.
Hex Name
0x01 Read coil
0x02 Read input
0x03 Read holding register
0x04 Read input register
0x05 Write single coil
0x06 Write single holding register
0x0F Write multiple coils
0x10 Write multiple holding registers
HI520
Description
Received function code can not be executed as an action by the controller.
Value contained in the data field is out of range or not allowed on the controller.
following a command:
Modbus Functions
40195 Holding
40195 Holding