BAST-421C-B2 BASstat BACnet® MS/TP Modulating Thermostat Installation Guide The BASstat series of BACnet-compliant wired communicating thermostats are BTL listed to ensure effortless integration into BACnet MS/TP (EIA-485) networks. These thermostats are suited for modulated heating, cooling, and ventilation with analog output control in 4-pipe applications such as Fan Coil Units (FCU) or Air Handlers. A configurable control algorithm allows adaptability to the specific application. This adaptive algorithm applied to the modulated valve control saves energy and ensures comfort for the occupants. Three sensing options are available: built-in temperature sensor, input for remote temperature sensor, or temperature override network command from Building Automation System. Occupancy status can be set from thermostat buttons, a wired ESI input, or over the BACnet network. Thermostat buttons can be locked to prevent tampering. Digital display with graphical icons is easy to read and understand. Numerous icons indicate parameters such as: Active Mode, Cooling, Heating, Ventilation Only, Fan Active, Occupied/Unoccupied state. Two control types are available: Cooling and Heating with Auto-changeover (default) and Cooling or Heating with Manual-changeover. NOTE: This unit is designed for 4-pipe HVAC systems and not recommended for 2-pipe HVAC systems. Installation The BASstat requires 24 VAC while drawing no more than 5 VA of power. The recommended conductor size is 16–18 AWG or 1.5mm 2 wires. WARNING: Internally, this device utilizes a half-wave rectifier and therefore can only share the same AC power source with other half-wave rectified devices. Sharing AC power with full-wave rectified devices is NOT recommended. Devices powered from a common AC source could be damaged if a mix of half-wave and full-wave rectified devices exists. The BASstat does not provide End-of-Line termination. If the BASstat 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 EIA-485 input terminal to avoid network errors or failure. BASstat mounts directly onto wall, panel, standard 65×65mm junction box (hole pitch 60 mm) or standard 2×4 inch vertical junction box (hole pitch 83.5 mm). To mount on electric box, separate back plate from the controller by loosening the screw. Align the mounting holes of the back plate to the screw holes of the electric box. Fix the back plate to the electric box using screws. Suggested screws for use are Phillips wide “truss head” or “washer head” screws #6-32 x ¾” (20mm). Wire the controller and mount on top of back plate. Secure by tightening the mount screw at the bottom. WARNING: DO NOT let the back-mount screw heads rise above the back plate or it may touch the circuit board and cause a short. Electrical (Class 2 Circuits Only) INPUT AC only Voltage (±10%): 24 VAC Power: 5 VA Frequency: 47-63 Hz Environmental Operating temperature: 0°C to 50°C Storage temperature: –10°C to +60°C Relative humidity: 5–95%, non-condensing Functional MS/TP Physical Layer: EIA-485 Cable length limit: 4000 ft/1200 m @76800 bps max MS/TP data rate (bps): 9600 – 76800 bps MS/TP node limit: 32 full-load devices max per segment BACnet MS/TP configuration requires setting the baud rate (9.6kbps – 76.8kbps) or using the default baud rate of 38.4kbps. A unique MS/TP MAC address is required to distinguish each thermostat from other MS/TP devices on the bus (default MAC address is 1). When more than one BASstat is installed at the same time on the same EIA-485 bus, their MAC addresses must be configured prior to communicating with all thermostats on the MS/TP bus, or communication will fail due to duplicate MAC addresses. The MAC address can be set from Engineering Menu item (Addr) with values of 1 – 127. The baud rate can be set from menu item (bAud) 9.6kbps – 76.8kbps. A unique Device Instance number throughout the entire BACnet internetwork is also required to distinguish the device from all other BACnet devices. Device instance can be modified in Engineering Menu items (dEVH) – high bytes – and (dEVL) – low bytes; Device Instance = (dEVH)*1000+(dEVL). Max masters setting can be set from menu item (AdrH), default value is 127. To enter the Engineering Menu, press the UP and DOWN buttons simultaneously for 5 seconds. Use the UP and DOWN buttons to navigate through the menu and change menu item values. Use the MODE button to enter a menu item and accept/confirm a selected value. To exit the Engineering Menu, navigate to menu item (End) and press MODE. The menu will also exit automatically 10 seconds after the last button is pressed. Mechanical Drawing Operation Overview 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 device over the BACnet network. Two control types are available: Cooling and Heating with Auto-changeover and Cooling or Heating with Manual-changeover. These control types are selectable from Engineering Menu (tyPE) or BACnet object MSV8. The default control type is Cooling and Heating with Auto-changeover. User-side comfort control is accomplished with six buttons – mode (Heat, Cool, or Ventilation – dependent on control type chosen from Engineering Menu (tyPE) or BACnet object MSV8), fan, raise, lower, set, and power. There are also options to lock select buttons or all buttons on the thermostat. A large LCD display indicates setpoint, space temperature, and current mode of operation using graphical icons. Reset settings can be performed from Engineering Menu item (rSt) which will reset all parameters including communication (MAC and Device Instance) and all control algorithm values back to factory-programmed defaults. For complete datasheet and details on BASstat, support, or compliance information, please download our BASstat User Manual and Data Sheet at: https://www.ccontrols.com/basautomation/basstat.php Free BACnet Discovery Tool for configuration: https://www.ccontrols.com/sd/bdt.htm Contemporary Control Systems, Inc. reserves the right to make changes in the specifications of the product described within this manual at any time without notice and without obligation of Contemporary Control Systems, Inc. to notify any person of such revision or change. TD150930-0IB Next >