The SC11S and SC25S analog signal conditioners convert a 0-10 VDC or 4-20 mA control signal to an output level capable of driving one or more Selectra modulating gas valves. A 3-position DIP switch configures the SC11S or SC25S for a 0-10VDC or 4-20mA input signal.The SC25S also monitors and limits minimum and maximum discharge air temperatures. The SC25S senses the discharge air temperature using a TS194 (Q) sensor with MT mixing tube. If the sensed discharge air temperature approaches the set minimum or maximum limit, the SC25S will override the control signal and reduce DC voltage (high limit) or increase DC voltage(low limit) in order to maintain discharge air temperaturesbetween the set limits. When measured discharge airtemperature is between the limit settings, the DC output isa function of the control signal (4-20 mA, 0-10 VDC) only.