The UVM can accept a digital input DP switch. The pneumatics of the DP switch are connected across the valve, and the factory supplied switch is set to trip at 0.6 in. W.C.
Any pressure across the valve below 0.6 in. W.C. is interpreted by the valve CFM as inaccurate or non-existent. The DP switch signal, when enabled in the UVM, provides a 0 CFM feedback signal if the pressure across the valve drops below the 0.6 in. W.C. threshold.
The DP switch functionality can also be implemented using a pressure sensor with a 0 V to 5 V output. The UVM can accept the 0 V to 5 V signal and, through user gain and offset settings, convert the signal to an internal pressure value.
A 0 in. to 4 in., or 5 in. W.C. sensor is used. When enabled in the UVM, this value can be compared to a minimum pressure value of 0.6 in. W.C. Like the DP switch, the feedback signal goes to 0 CFM.
The UVM can also operate with a variable air volume (VAV) box instead of a Venturi valve. Instead of a CFM request signal provided to the UVM, the input is interpreted as an actuator position signal where 0 V to 10 V represents a 0% to 100% position signal.
This signal provides position information for the VAV box only. The feedback sensor signal is replaced by the VAV box flow probe pressure signal. This voltage signal is scaled and converted to an internal pressure value.
The square root of the pressure value is calculated and multiplied by a K factor to obtain an internal velocity value. The velocity value is multiplied by a duct area value to obtain an internal CFM value. This CFM value is scaled to the appropriate voltage and passed to the Vo feedback voltage signal for use by the third-party controller. The scaling, K factor, and area can be set by the user with the UVM Configuration Tool.
Other than through the UVM Configuration Tool, the user does not have access to any UVM settings or operation modes. The exception is that the input and output signal modes and the normal or reverse operation can be set via the DIP switches if the functionality is enabled in the UVM.
The inputs and outputs can be set to be interpreted as a percentage (0 V to 10 V = 0% to 100%) control or feedback signal, or as a CFM (0 V to 10 V = 0 CFM to xxxx CFM ) control or feedback signal. DIP switches 6 and 7 are used for this function. DIP switch 5 is normal reverse selection.
The UVM can communicate with the UVM Configuration Tool. The UVM can reside at one of 16 hardware addresses. These addresses are set by DIP switches 1 to 4. Through the UVM Configuration Tool, the UVM can have a maximum of 16 additional software addresses set for communications use.
The later S series versions can configure to sum CFMs over the RS485 network and output the summed equivalent on the Vo of the unit designated to be primary. The primary unit is designated with hardware address 15. Secondary polled units are designated with address 16 and upwards. The primary unit specifies how many units to poll from address 16 on-wards.