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CONTEMPORARY CONTROLS BAST-421C-B2 BACnet Communicating Thermostat 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.  
3.1 Terminal Block Pin Assignments  
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  
Comment  
24 VAC high-side  
24 VAC common  
Number Mark  
Comment  
AO1 Cooling Device  
COM  
1
2
3
4
5
6
7
8
9
R
C
10  
11  
12  
13  
14  
15  
16  
17  
18  
AO2 Heating Device  
RS Remote Sensor Input  
COM Sensor Common  
ESI Energy Saving Input  
D+  
D-  
RS-485 Positive  
RS-485 Negative  
G
Fan  
3.2 Limited Power Source  
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).  
3.3 Power Supply Precautions  
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  
Page 9  
UM-15093000-AA2  
GeneralDetails
NameCONTEMPORARY CONTROLS BAST-421C-B2 BACnet Communicating Thermostat User Manual
MakeCONTEMPORARY CONTROLS
LanguageEnglish
FiletypePDF (Download)
File size0.65 MB
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CONTEMPORARY CONTROLS BAST-421C-B2 BACnet Communicating Thermostat User Manual