schmersal Praxi 100, Manual

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Function
(dec)
Function
(hex)
Modbus Function Name
TCP/
UDP
RTU Access type
Address
range (hex)
1 1 Read coils x Discrete (1-bit) 00000-0FFFF
2 2 Read Discrete Inputs x Discrete (1-bit) 10000-1FFFF
3 3 Read Holding Registers x x Register (16bit) 40000-4FFFF
4 4 Read Input Registers x x Register (16bit) 30000-3FFFF
5 5 Write Single Coils x Discrete (1-bit) 00000-0FFFF
6 6 Write Single Register x x Register (16bit) 40000-4FFFF
15 F Write Multiple Coils x Discrete (1-bit) 00000-0FFFF
16 10 Write Multiple Registers x x Register (16bit) 40000-4FFFF
23 17 Read/Write Multiple Registers x x Register (16bit) 40000-4FFFF
6. Communications
Features of the Modbus-Praxi interface:
■
Direct control of Praxi drive (e.g. Run, Stop, Direction, Speed reference, Fault reset)
■
Full access to all Praxi parameters
■
Monitor Praxi status (e.g. Output frequency, Output current, Fault code)
All data addresses in Modbus messages are referenced to zero. The first occurrence of a data item is addressed as item
number zero. For example:
■
The coil known as ‘Coil 1’ in a programmable controller is addressed as ‘Coil 0000’ in the data address field
of a Modbus message.
■
Coil 127 decimal is addressed as ‘Coil 007E hex’ (126 decimal).
■
Holding register 40001 is addressed as register 0000 in the data address field of the message. The function
code field already specifies a ‘holding register’ operation. Therefore the ‘4XXXX’ reference is implicit.
■
Holding register 40108 is addressed as register 006B hex (107 decimal).
The Praxi variables and fault codes as well as the parameters can be read and written from Modbus. The parameter
addresses are determined in the application. Every parameter and actual value have been given an ID number in the
application. The ID numbering of the parameter as well as the parameter ranges and steps can be found in the application
manual in question. The parameter value must be given without decimals. If several parameters/actual values are read
with one message, the addresses of the parameters/actual values must be consecutive.
NOTE! Broadcasting not supported in TCP.
Broadcast supported with function code 06 and 16 in RTU and in UDP.
The address ranges of the different function codes are in many cases not relevant to the user and can be ignored. The
targeted information type (coil, register etc.) can be selected separate from the address.
Table 15. Supported functions
6.1 Data Addresses in Modbus Messages
6.2 Supported Modbus Functions