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General data of the Modbus RTU interface
Redundant line topology:
Possible cable length with repeat-
er (total network cable length)
Max. cable length (segment
length) without repeater
Baud rate (kbit/s)
approx. 10 km
1,200 m
9.6 – 115.2
Redundant ring topology:
Max. possible cable length of re-
dundant loop
Max. cable length between actuat-
ors (without repeater)
Baud rate (kbit/s)
approx. 290 km
1,200 m
9.6 – 115.2
Transmission rate/cable length
Modbus slave, e.g. devices with digital and/or analogue inputs/outputs such as actuators, sensors
Device types
32 devices in each segment without repeater, with repeaters expandable to 247
Number of devices
Polling between master and slaves (query response)
Fieldbus access
01 Read Coil Status
02 Read Input Status
03 Read Holding Registers
04 Read Input Registers
05 Force Single Coil
15 (0FHex) Force Multiple Coils
06 Preset Single Register
16 (10Hex) Preset Multiple Registers
17 (11Hex) Report Slave ID
08 Diagnostics:
●
00 00 Loopback
●
00 10 (0AHex) Clear Counters and Diagnostic Register
●
00 11 (0BHex) Return Bus Message Count
●
00 12 (0CHex) Return Bus Communication Error Count
●
00 13 (0DHex) Return Bus Exception Error Count
●
00 14 (0EHex) Return Slave Message Count
●
00 15 (0FHex) Return Slave No Response Count
●
00 16 (10Hex) Return Slave NAK Count
●
00 17 (11Hex) Return Slave Busy Count
●
00 18 (12Hex) Return Character Overrun Count
Supported Modbus functions (ser-
vices)
Commands and signals of the Modbus RTU interface
OPEN, STOP, CLOSE, position setpoint, RESET, EMERGENCY operation command, enable LOCAL,
Interlock OPEN/CLOSE
Process representation output
(command signals)
●
End positions OPEN, CLOSED
●
Actual position value
●
Actual torque value, requires MWG in actuator
●
Selector switch in position LOCAL/REMOTE
●
Running indication (directional)
●
Torque switches OPEN, CLOSED
●
Limit switches OPEN, CLOSED
●
Manual operation by handwheel or via local controls
●
Analogue (2) and digital (4) customer inputs
Process representation input (feed-
back signals)
●
Motor protection tripped
●
Torque switch tripped in mid-travel
●
One phase missing
●
Failure of analogue customer inputs
Process representation input (fault
signals)
The behaviour of the actuator is programmable:
●
Stop in current position
●
Travel to end position OPEN or CLOSED
●
Travel to any intermediate position
●
Execute last received operation command
Behaviour on loss of communication
94
SQVEx 05.2 – SQVEx 14.2/ SQRVEx 05.2 – SQRVEx 14.2 Control unit: electronic (MWG)
Technical data
ACVExC 01.2 Modbus RTU