AB-7350-U
19
Solid line: Isolated,
Dashed line: Not isolated
Power
Internal circuit
T1 (Supply water temperature)
T2 (Return water temperature)
Pulse output
Display Panel
DI (Cooling/heating switch signal)
RS-485 communication In
Control signal input
RS-485 communication Out
Figure 20. Internal isolation
6. Single transformer with two products (See Fig. 21.):
Connect the lines from the terminal 1 of each product to the transformer with the same polarity. Connect the lines from the
terminal 2 of each product the same way. If the terminals (of the product and the transformer) with different polarities are
connected, the products may get damaged.
7. Single controller with multiple 4 to 20 mA input type products (See Figs. 22 and 23.):
4 to 20 mA control signal input is not isolated from the power, and the 4 to 20 mA input impedance is 250
Ω
. For connecting
a controller, the relations among the input impedance of this product, the output load resistance of the controller, and the
output load resistance and input impedance of an isolator (if necessary) must meet the following formula.
Applicable load resistance > Total input impedance
To operate the two products with a single controller for example, refer to Fig. 22 for the two products powered by a single
transformer, and refer to Fig. 23 for the two products separately powered by the two transformers. To connect a single
transformer, be sure to connect an isolator to the 4 to 20 mA input terminal of the second product. The products will
malfunction without the isolator.
