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Modbus Rtu Cable; Modbus Tcp Cable; Modbus Rtu And Tcp Electrical Connections - Honeywell TPPL Modbus TCP Installation And Setup Manual

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3.1 Modbus RTU Cable

The Modbus RTU cable should be Belden 3105A (22 AWG) or similar shielded data communication cable connected to a
router operating at 4800 Baud minimum (>9600 Baud preferred).

3.2 Modbus TCP Cable

The Modbus TCP cable should be CAT 5/5E or higher shielded data communication cable suited to the installation
distance and ambient environment factors.
In addition:
Spurs shall not be longer than 1m each, and shall not exceed 10m combined total length.
The maximum cable length without line repeaters is 1.2km (1200 m, 1300 yd).
The maximum wire size is 1.5 mm

3.3 Modbus RTU and TCP Electrical Connections

The electrical connections are shown below:
Some transceiver manufacturers have been known to incorrectly reverse their RS485 Data terminals, which can
cause Tx/Rx to fail. If this happens, simply swap over the TPPL's A and B cables and then re-test.
Note: You should connect a 120Ω termination resistor (R
TPPL is the last node in a Modbus system highway.
Note: The external R
MAN0995_Iss 1_01/16
Pt. No. 3011M5027_1
M
ODBUS
(15 AWG).
2
MODBUS RTU
Label
Drain
D
Data +
A (D+)
Data -
B (D-)
Figure 3.
Modbus RTU Connections
is not needed if the logic solver side has an internal R
T
I
NSTALLATION
Caution
Terminal ID
Logic Solver
1
2
3
) between A and B to prevent reflections on the RS485 circuit if
T
.
T
8
D
A (D+)
B (D-)
Touchpoint Plus
Modbus Installation Guide

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