The Series GSTC Carbon Monoxide/Nitrogen Dioxide Gas Transmitter monitors the gas concentration in underground parking garages and loading docks. The carbon monoxide transmitter is used to measure the exhaust of gasoline engines, while the nitrogen dioxide transmitter is used for diesel engines. The Series GSTC is compatible with either BACnet or MODBUS® communication protocol, allowing the transmitter to be used with almost any building management controller. The GSTC output is communicated over an RS-485 wire via BACnet or MODBUS® communication protocol. To maximize the accuracy of the Series GSTC, the sensor can be field-calibrated using the A-449 remote LCD display. When the sensor reaches the end of its life, the display will indicate that the sensor needs to be replaced. BACnet and MODBUS® communication protocol recommend limiting the number of nodes in any segment to 32. Therefore, the transceiver may be rated at one unit load. Fractional loads are also acceptable. The Series GSTC accounts as an eighth of a load on the MSTP network.