Introduction - Contemporary Controls BASstat BAST-121C-B2 User Manual

1 Introduction

The BAST-121C-B2 is a member of the BASstat BACnet Communicating Thermostat series. It
provides multi-stage heating only or cooling only control in an attractive wall-mounted enclosure
with a large LCD display. Intended for use with single mode heating and cooling units, the
thermostat can control one or two stages of heating, one or two stages of Direct Expansion (DX)
cooling, or a single 0-10V control output for either modulated heating or cooling. The BASstat is
BACnet compliant and BTL listed to ensure easy integration into BACnet networks using
BACnet/MS/TP over 2-wire EIA-485. The BAST-121C-B2 can be routed to BACnet/IP clients
using a BASrouter (BASRT-B). A large, easy to read LCD display indicates setpoint, space
temperature and current mode of operation using graphical icons.
The BASstat has a built-in space temperature sensor with provision for remote wired 3kΩ NTC
thermistor sensor or temperature value can be sent by another communicating device over the
BACnet network. The BAST-121C-B2 has three relays - two for staged heating or cooling
(depending upon operating mode) and one for fan. The BAST-121C-B2 has a single 0-10V
modulated output to control a single analog heating or cooling output device. The BASstat is
configurable locally using the Engineering Menu or via a network connection to a BACnet client.
Contemporary Controls' free BACnet Discovery Tool can be used for initial discovery and
configuration of the thermostat over the network. Control algorithm parameters such as
proportional gain, integral rate and trip points are all configurable. This BASstat also features
configurable fan control and occupancy selection. Operating states are indicated on the
thermostat display.
The features available in the BASstat can be configured by the systems integrator to meet user
requirements in two different ways. One way is using a button sequence on the thermostat in
order to enter the Engineering Menu - which requires physical access to the thermostat.
Optionally, the buttons could be locked to limit user access to the Engineering Menu after
installation is complete. The second method is configuring the thermostat over the BACnet
network using a BACnet client device or software such as Contemporary Controls' free BACnet
Discovery Tool. Most features available are configurable using both methods.
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