Temperature Control Programming Example
A TCU is used to control the temperature of cooking kettles at a food
processing f acility. The 4-20 mA linear DC output is used to control a steam
valve which provides the heat to the kettles. The following is a list of the
process requirements and the subsequent parameter values keyed-in to the
controller.
Process Requirements
Output: Linear DC 4-20 mA. Limit to 70% of maximum
power
Update Time: 5 seconds
Deadband: 2%
Input: type t thermocouple °F
Open Response: Valve off
Setpoint Range: 150°F to 300°F
Alarms: 10° and 20° deviation band alarms, Auto reset
10° band, latch 20° band, disable alarms during
startup
User Inputs: Integral Action Lockout
Configure Input Parameters
tYPE t Thermocouple type “T”
SCAL °F Control and indicate in °F
dCPt 0 One degree display resolution
FLtr 2 Increased input signal digital filtering
SPAN 1.000 No span correction necessary
SHFt 0 No shift correction necessary
SPLO 150 Limit min. setpoint temperature to 150°F
SPHI 300 Limit max. setpoint temperature to 300°F
SPrP 0.0 No setpoint ramping
InPt Lock Integral Action via User Input
Configure Output Parameters
CYCt 0 Not using time proportioning output
OPAC rEv Use reverse acting for heating
OPLO 0% Low power limit of 0%
OPHI 70% High power limit of 70% to reduce temperature
change shock
OPFL 0% Turn valve off if probe failure
OPdP 3 sec Output power dampening = 3 seconds
CHYS - Not using on/off control
tcod 0 select fastest response
ANAS OP Linear DC output used for control
ANLO 0.0% Steam valve provides full deflection for 4-20 mA
signal range
ANHI 100.0%
Andb 2.0% Impose 2% deadband on Linear DC Output
ANut 5 sec Update output once every 5 seconds
Configure Alarm Parameters
Act1 b-ot Set alarm #1 for deviation band from setpoint
rSt1 auto Automatic reset
Stb1 yes Disable alarming during power-up
AL-1 10 Set 10° alarm value
Act2 b-ot Set alarm #2 for deviation band from setpoint
rst2 LATC Manual reset
stb2 YES Disable alarm during power-up
AL-2 20 Set 20° alarm value
AHYS 1 1° alarm activation hysteresis
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