Robertshaw Smart Sense Series Installation Manual page 45

The communications port of the SMART 2000 has two terminals marked
A and B. See Figure 24. Terminals A+ and B- are used for communication.
A maximum of 32 SMART 2000 thermostats can be connected to any single hub.
Each thermostat on the hub must have a unique network address (factory default
is 7). These settings are adjustable from 1 to 99 in the Advanced Installer Menu.
A typical ModBus wiring example is shown in Figure 25. If using a common power
supply to power all thermostats on a network, it is highly recommended that all
power is wired in phase, i.e. R to R and C to C and NOT crossed.
Figure 24
ModBus
Thermostat
Master
Power COMS
24 24C B A T
B -
A +
Figure 25
Thermostat Thermostat
Power COMS Power COMS
24 24C B A T 24 24C B A T
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