Siemens SINAMICS G120 CU240B-2, Operating Instructions Manual, Page: 150 / 290

Connection to a fieldbus
6.4 Communication via RS485
Inverter with CU240B-2 and CU240E-2 Control Units
150
Operating Instructions, 07/2010, FW 4.3.2, A5E02299792B AA
Modbus
Reg.
No.
Description Modb
us
acces
s
Unit Scaling
factor
On/Off text
or value range
Data / parameter
Technology controller adjustment
40510
Time constant for actual value filter of
the technology controller
R/W -- 100 0.00 … 60.0 p2265
40511 Scaling factor for actual value of the
technology controller
R/W % 100 0.00 … 500.00 p2269
40512 Proportional amplification of the
technology controller
R/W -- 1000 0.000 … 65.000 p2280
40513 Integral time of the technology
controller
R/W s 1 0 … 60 p2285
40514 Time constant D-component of the
technology controller
R/W -- 1 0 … 60 p2274
40515 Max. limit of technology controller R/W % 100 -200.0 … 200.0 p2291
40516 Min. limit technology controller R/W % 100 -200.0 … 200.0 p2292
PID diagnostics
40520
Effective setpoint acc. to internal
technology controller MOP ramp-
function generator
R % 100 -100.0 … 100.0 r2250
40521 Actual value of technology controller
after filter
R % 100 -100.0 … 100.0 r2266
40522 Output signal technology controller R % 100 -100.0 … 100.0 r2294
6.4.3.4 Write and read access via FC 3 and FC 6
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)
All valid register addresses are permitted as a start address. If a register address is invalid,
exception code 02 (invalid data address) is returned. An attempt to read a write-only register
or a reserved register is replied to with a normal telegram in which all values are set to 0.
Using FC 03, it is possible to address more than 1 register with one request. The number of
addressed registers is contained in bytes 4 and 5 of the read request.
Number of registers
If more than 125 registers are addressed, exception code 03 (Illegal data value) is returned.
If the start address plus the number of registers for an address are outside of a defined
register block, exception code 02 (invalid data address) is returned.