APPENDIX 1 - TECHNICAL SPECIFICATION
Temperature & Humidity Programmer/Controller with inbuilt Logic, chamber
intelligence mapping, & Data Logging
Operator interface data entry: on-chamber dedicated numeric keypad,
display: on-chamber (green) monochrome CRT.
Operating temperature: 5°C to 60°C.
Analogue inputs Two 4 wire PRT inputs. Range -150°C to +350°C. Accuracy +/-
0.1°C. Dedicated to measuring temperature and humidity (relative humidity is de-
rived by wet & dry bulb by psychrometric computation).
Calibration of the analogue inputs: performed in software; there are no presets to ad-
just.
Control Loops
Temperature. Three term (P.I.D.) digital control, using trapezoidal approximation to in-
terpolate between samples. Input sample and control period is 4 seconds. Output of
control algorithm is heat digital mark space ratio (with -100% to +100% dead band
adjustment). Set point resolution 0. loC.
Relative Humidity. Three term (P.I.D.) digital control, using trapezoidal approximation
to interpolate between samples. Input sample and control period is 4 seconds. Out-
put of control algorithm is humidify digital mark space ratio (with -100% to +100%
dead band adjustment). Set point resolution 1 %RH.
Controller Intelligence For all regions of the chamber performance envelope, a table
pre-stores:
a map of appropriate "housekeeping" facilities
a map of appropriate P.I.D. controller coefficients.
Maps are not displayed on the controller. Housekeeping: Digital channel selection: by
autosuggestion from intelligence at setpoint entry. Over-ride: available at keypad.
Internal Defrost Clock: Invoked automatically if required (from intelligence).
Steady State Control The controller allows set point values to be entered for tempera-
ture and humidity. With autosuggested or manually input digital channel selections.
Programs
Library capacity: 20 programs nominal (leaves space for 1 week log) program size: 150
lines/segments max per program, 10 kbytes approx per program, segment/line con-
tent: time + any of: temperature, humidity, digital channel, loop
time basis: time from program start
time units: days, hours, minutes, seconds
editing facilities: line cut; paste; block copy
loop:
facility to repeat program sections
nesting: (loops within loops) supported
file facilities: save, load, delete
precondition: line 000 omits after 1st cycle.
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