MIC 1400 Manual
Edition 1
35
Direct/Reverse Operation of Outputs 4.3
Direct operation is typically used with cooling applications. On-Off direct
output(s) will turn on when the process variable exceeds setpoint. Propor-
tional direct output(s) will increase the percentage of output as the process
value increases within the proportional band.
Reverse operation is typically used with heating applications. On-Off re-
verse output(s) will turn off when the process variable exceeds setpoint.
Proportional reverse output(s) will decrease the percentage of output as the
process value increases within the proportional band.
Output 2 will be Direct when Output 1 is selected as Reverse and Reverse
when Output 1 is selected as Direct.
On-Off Control 4.4
On-Off control can be implemented with SPDT relay or SSR driver
output(s) by setting the corresponding proportional band (Pb) to 0.0. On-
Off operation can be assigned to Output 1 only (Output 2 not present),
Output 1 AND Output 2, or Output 2 only (Output 1 is time proportional or
current proportional). A hysteresis adjustment is provided for On-Off out-
puts, "HyS1" for Output 1 only, "HySt" for Output 1 AND Output 2, or
"HyS2" for Output 2 only. This adjustment is in % of input span and defines
the bandwidth of the hysteresis. Relay chatter can be eliminated by proper
adjustment of this parameter. When operating in On-Off control, the
output(s) will turn on or off depending upon the setpoint, the process value,
and the hysteresis adjustment.
