Write And Read Access Via Fc 03 And Fc 06 - Siemens SINAMICS G120 Operating Instructions Manual

Modbus Description
Reg. No.
40513 Integral time of the technology
controller
40514 Time constant D-component of the
technology controller
40515 Max. limit of technology controller
40516 Min. limit technology controller
PID diagnostics
40520 Effective setpoint acc. to internal
technology controller MOP ramp-
function generator
40521 Actual value of technology
controller after filter
40522 Output signal technology controller
7.7.3.4

Write and read access via FC 03 and FC 06

Function codes used
For data exchange between the master and slave, predefined function codes are used for
communication via Modbus.
The Control Unit uses the Modbus function code 03, FC 03 (read holding registers) for
reading, and the Modbus function code 06, FC 06 (preset single register) for writing.
Structure of a read request via Modbus function code 03 (FC 03)
Any valid register address is permitted as the start address.
The controller can access more than one register via FC 03 with a request. The number of
addressed registers is contained in bytes 4 and 5 of the read request.
Table 7- 19
Read request
Invalid register address
Read a write-only register
Read a reserved register
Controller addresses more than 125 registers
The start address and the number of registers of an
address are located outside of a defined register block
Converter with the CU250S-2 Control Unit (vector)
Operating Instructions, 06/2013, FW V4.6, A5E31759476B AB
Modbus
access
R/W
R/W
R/W
R/W
R
R
R
Invalid read requests
Unit Scaling On/Off text
factor
or value range
s 1 0 ... 60
-- 1 0 ... 60
% 100 -200.0 ... 200.0
% 100 -200.0 ... 200.0
% 100 -100.0 ... 100.0
% 100 -100.0 ... 100.0
% 100 -100.0 ... 100.0
Converter response
Exception code 02 (invalid data address)
Telegram in which all values are set to 0.
Exception code 03 (invalid data value)
Exception code 02 (invalid data address)
Configuring the fieldbus
7.7 Communication via RS485
Data / parameter
p2285
p2274
p2291
p2292
r2250
r2266
r2294
175