User Manual

Page 19
Data Format
Protocol Modbus RTU (Slave)
Byte Format 1 Start Bit, 8 Data Bits, 1 Stop Bit, No Parity
Address 1 to 255
Baud 4800 / 9600 / 19200 BPS
Holding
Register
Type
Value
Comments
40001
Read Only
Device ID
Always Returns “131”
Use as A Sentinel Point
40002
Read Only
Firmware Version
Divide By 100 (e.g. Version 2.36 = 236)
40003
Read Only
DIP Switch State
Binary Count
Sw 1 = 1, Sw2 = 2, Sw3 = 4, Sw 4 = 8 etc
40004
Read /
Write
Occupancy Status
0 = Room is Unoccupied
1 = Room is Occupied
Note - Modbus can write “0” holding the
room unoccupied regardless of the occupancy
input.
Modbus cannot override the occupancy input
and hold the SMT-131 in occupied mode.
40005
Read Only
Bell Status
0 = Bell Is Silent
1 = Bell Is Chiming
40006
Read /
Write
Door Station Status
0 = Normal - No Activity
1 = “Make Up Room” Active
2 = “Do Not Disturb” Active
40007
Read /
Write
HVAC Status
0 = Air Conditioning Off (1 or 3 Fan Speed)
1 = Low Speed Ventilation (1 or 3 Fan Speed)
2 = Med Speed Ventilation (3 Fan Speed Only)
3 = High Speed Ventilation (3 Fan Speed only)
4 = Air Conditioning ON (1 or 3 Fan Speed)
40008
Read /
Write
Fan Status
3 Fan Speed Mode
0 = Low (Fan Auto)
1 = Med (Fan Auto)
2= High (Fan Auto)
3 = Auto Fan Speed (Fan Auto)
4 = Low (Fan On)
5 = Med (Fan On)
6 = High (Fan On)
7 = Auto Fan Speed (Fan On)
1 Fan Speed Mode
0 = Fan Auto
4 = Fan On
40009
Read /
Write
User Set Point
Deg C = 0.5°C Steps
Deg F = 1°F Steps
Value / 10 ( e.g. 23.5°C = 235)
40010
Read /
Write
Contact Reception
Notification
0 = Off
1 = Show Contact Reception on LCD
SMT-131 LCD will flash “Contact Reception”
on LCD and sound chime. User may accept
alert by touching any button on SMT-131