Modbus Rs485 Information; Function Codes - Endress+Hauser Proline Prosonic Flow P 500 Operating Instructions Manual

System integration
86
Compatible Modbus registers: diagnostic information
Diagnostic information
Diagnostic code (data type: String), e.g. F270
Diagnostic number (data type: Integer), e.g. 270
The Modbus registers are compatible but the diagnostic numbers are not. Overview of
the new diagnostic numbers →  159.
9.3

Modbus RS485 information

9.3.1

Function codes

Function codes are used to define which read or write action is carried out via the Modbus
protocol. The measuring device supports the following function codes:
Code Name
03 Read holding
register
04 Read input
register
06 Write single
registers
08 Diagnostics
Proline Prosonic Flow P 500 Modbus RS485
Compatible Modbus registers
6821
6859
Description
Master reads one or more Modbus
registers from the device.
A maximum of 125 consecutive
registers can be read with 1
telegram: 1 register = 2 bytes

The measuring device does
not make a distinction
between function codes 03
and 04; these codes therefore
yield the same result.
Master reads one or more Modbus
registers from the device.
A maximum of 125 consecutive
registers can be read with 1
telegram: 1 register = 2 bytes

The measuring device does
not make a distinction
between function codes 03
and 04; these codes therefore
yield the same result.
Master writes a new value to one
Modbus register of the measuring
device.

Use function code 16 to write
multiple registers with just 1
telegram.
Master checks the communication
connection to the measuring device.
The following "Diagnostics codes"
are supported:
• Sub-function 00 = Return query
data (loopback test)
• Sub-function 02 = Return
diagnostics register
Application
Read device parameters with read
and write access
Example:
Read volume flow
Read device parameters with read
access
Example:
Read totalizer value
Write only 1 device parameter
Example: reset totalizer
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