Response to a read coil status command, Read input status command (02) – Flowserve L75 Series Electric Actuator User Manual
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L75 Series Electric Actuator — Modbus RTU FCD LMAIM7502-00 – 07/05
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Response to a Read Coil Status Command
A response to a correct reception of the command would have the data field set to either 00 (not driving
in the specified direction) or 01 (actively driving in the specified direction). The example response below
shows the CW motion control circuit is actively driving the valve in the CW direction.
Field Name
Example
Actuator Address
05
Function (Read Coil Status)
01
Byte Count
01
Data
01
CRC Error Check (LS byte)
91
CRC Error Check (MS byte)
78
The bytes sent (in hex) to the master in the above example would be: 05,01,01,01.91,78
If coil 1 (CW) is specified and 2 points are requested, the data is packed into one byte of data where coil
1 (CW) status is bit 0 and coil 2 (CCW) status is bit 1 of the byte. If coil 2 (CCW) status is requested,
only one point can be specified and is returned in bit 0.
Data Byte When 2 Coil Statuses are Read
7
6
5
4
3
2
1
0
Status
0
0
0
0
0
0
0
0
Valve is not being driven in either direction.
0
0
0
0
0
0
0
1
Valve is being driven in the CW direction.
0
0
0
0
0
0
1
0
Valve is being driven in the CCW direction.
0
0
0
0
0
0
1
1
This status value is not possible.
Read Input Status Command (02)
This command reads the state of one or both end-of-travel limit switches. The CW limit switch detects
end-of-travel in the clockwise direction and is at register location 10001; the CCW limit switch detects
end-of-travel in the counterclockwise direction and is at register location 10002. Both locations can be
requested by reading two register locations starting at location 10001 or the locations can be requested
separately. Broadcast is not supported.
Example: “Read the status of both limit switches on actuator #5”
Field Name
Example
Actuator Address
05
Function (Read Input Status)
02
Starting Address (High)
00
Starting Address (Low)
00
Number of Points (High)
00
Number of Points (Low)
02
CRC Error Check (LS byte)
F8
CRC Error Check (MS byte)
4F
The bytes sent (in hex) to the actuator in the above example would be: 05, 02, 00, 00, 00, 02, F8, 4F