Installation; Terminal Block Pin Assignments; Limited Power Source; Power Supply Precautions - Contemporary Controls BASstat BAST-421C-B2 User Manual

3 Installation

The BASstat 421C-B2 is intended for surface-mount installation on an interior wall, away from
direct sunlight or direct air movement. The display (top half) can be removed from its base by
loosening the small Philips screw at the bottom of the display. Once the display is removed
from the base, the base can be mounted onto the wall with appropriate fasteners. If a single-
gang electrical junction box is to be used, the top and bottom mounting holes will align with the
screw holes in the junction box.

Terminal Block Pin Assignments

3.1
Two terminal blocks provide for all field connections. BACnet MS/TP data communication
connections can be found at terminals 16 and 17 and are polarity sensitive. This BASstat does
not provide End-of-Line termination. If the BASstat-421C-B2 is the first or last device on the
MS/TP bus, a termination resistor (120Ω) must be applied across pins 16 and 17 of the input
terminal. The remote sensor input (RS) is at terminals 13 and 14. The remote occupancy (ESI)
input is a dry contact closure input located at terminals 14 and 15.
Number Mark
1 R 24 VAC high-side
2 C 24 VAC common
3
4
5
6
7
8 G Fan
9

Limited Power Source

3.2
The BASstat is intended to be powered by a Class 2 compliant power source and only accepts
24VAC with no more than 5VA of power consumption. It should be powered by a Class 2 power
source complying with the requirements of the National Electric Code (NEC) article 725. The
transformer or power supply complying with the Class 2 rating must carry a corresponding listing
from a regulatory agency such as Underwriters Laboratories (UL).

Power Supply Precautions

3.3
Internally, the BASstat utilizes a half-wave rectifier and can share the same AC power source
with other half-wave rectified devices. Sharing AC power with full-wave rectified devices is NOT
UM-15093000-AA1
Comment Number Mark
10 AO1 Cooling Device
11 COM
12 AO2 Heating Device
13 RS Remote Sensor Input
14 COM Sensor Common
15 ESI Energy Saving Input
16 D+ RS-485 Positive
17 D- RS-485 Negative
18
Comment
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