Control functions
7.8 Communicating with the PLC
SINAMICS V90, SIMOTICS S-1FL6
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Operating Instructions, 04/2019, A5E36037884-007
7.8
Communicating with the PLC
The SINAMICS V90 supports communication with the PLC on the RS485 interface. You can
parameterize whether the RS485 interface applies USS or Modbus RTU protocol. USS is the
default bus setting. A shielded twisted pair cable is recommended for RS485 communication.
7.8.1
USS communication
The SINAMICS V90 can communicate with the PLC through an RS485 cable with the
standard USS communication protocol. After the communication is established, you can
change the position setpoint and speed setpoint through the USS communication protocol.
The servo drive can also transmit the actual speed, torque, and alarm to the PLC through the
USS communication protocol.
Telegram format
The telegram format is shown as follows:
STX
LGE
ADR
PKE
IND
PWE
PWE
BCC
STX: start of text
LGE: length
ADR: slave address
PKE: parameter ID
IND: sub-index
PWE: parameter value
BCC: block check character
Relevant parameters
You can access the following parameters by USS.
Parameter
Description
Parameter
Description
p1001
Fixed speed setpoint 1
r0020
Speed setpoint smoothed
p1002
Fixed speed setpoint 2
r0021
Actual speed smoothed
p1003
Fixed speed setpoint 3
r0026
DC link voltage smoothed
p1004
Fixed speed setpoint 4
r0027
Absolute actual current smoothed
p1005
Fixed speed setpoint 5
r0031
Actual torque smoothed
p1006
Fixed speed setpoint 6
r0032
Active power actual value smoothed
p1007
Fixed speed setpoint 7
r0034
Motor utilization thermal
p2617[0...7]
Fixed position setpoint
r0807
Master control active
p2618[0...7]
Speed of fixed position setpoint
r2521
LR position actual value
p2572
IPos maximum acceleration
r2556
LR position setpoint after setpoint
smoothing
p2573
IPos maximum deceleration