Extron’s BusMux Pro HD is a UL approved and intrinsically safe temperature multiplexer Suitable for use in Class I, II and III and Groups A-G hazardous locations. The BusMux Pro HD is compatible with any standard, off the shelf thermocouple signals and 4-20mA, mV or RTD signals.
We use this same technology in both our Hazard Monitoring and Grain Temperature applications but utilize a different input card.
- Grain Temperature: Wireless or hardwired to PLC
- Hazard Monitoring: Hardwired to PLC
Input Card Overview
The Input Card reads the value of the connected sensor and then converts it to temperature and resistance. The card also performs Open, Shorted, Warning Temperature, Alarm Temperature, and Rate of Rise calculations.
The input card reads the raw value from the connected sensor and then converts it to a temperature. If a major fault condition occurs, error codes will be place into the temperature registers.
The input card measures the resistance of the connected sensor to determine the quality of the cable and sensor. If the resistance is greater than the maximum value the card can read, a fault code will be placed resistance register.
If the sensor has a high resistance or the connection is broken, the input card will set an Open Status fault. In an Open condition, the temperature will display a fault code of 32767.
Rate of Rise – Hazard Monitoring
Rate of rise looks at a temperature change over a period of time. If the change is greater than the set point, a Rate of Rise status fault will be set. The input card is able to have two rate of rise set points: Alarm and Warning.
If the connected sensor is a thermocouple and the resistance drops below a certain amount the thermocouple is considered shorted. The amount the resistance can drop is determined by the Base Resistance set point and the Resistance Tolerance set point. If the connected sensor is an RTD and the resistance drops below 50 ohms, the sensor is considered shorted.
Capacity of 84 thermocouples Capacity of 42 thermocouples
System Capacity of 672 T/C’s System Capacity of 338 T/C’s