Honeywell Touchpoint Plus Technical Handbook page 51

System Electrical Installation
2) Slide the cover off carefully and place it on a clean, anti-static surface.
3) Fit the Modbus PCB by carefully aligning the connectors and pushing down gently, observing the orientation shown
below:
4) Connect the Modbus cables as shown below. (You should connect a 120Ω termination resistor (R
to prevent reflections on the RS485 circuit if TPPL is the last node in a Modbus system highway.)
Note: External R
Some manufacturers have been known to incorrectly reverse their RS485 Data terminals, which can cause Tx/Rx
MAN0984_Iss 3_02/16
Pt. No. 3011M5001_3
Figure 41. Motherboard Showing the Modbus PCB Location
is not needed if the logic solver side has an internal R
T
to fail. If this happens, simply swap over A and B cables and re-test.
MODBUS RTU Label
Drain D
Data + A (D+)
Data - B (D-)
Touchpoint Plus Touchpoint Plus
MODBUS RTU MODBUS RTU
Figure 42. Modbus RTU Connections
Modbus
PCB
Modbus RTU
Terminals
.
T
CAUTION
Terminal ID
1
2
3
Logic Solver
43
B↔
Logic
A↔
Solver
D↔
Ethernet
Connector
) between A and B
T
Logic Solver
D
A (D+)
B (D-)
Technical Handbook
Touchpoint Plus