Despatch Protocol Plus Controller (Heat/Cool) - Manual (Page 7)

1
INTRODUCTION
The special features of the Protocol Plus
TM
control include:
•
PID tuning
•
Ramp/Soak programming of up to 64 segments
•
Segment looping and profile linking
•
Built-in manual reset high limit control
•
Built-in process timer
•
Dedicated LED display for process temperature
•
Multi-purpose two-line LCD display with backlight
•
Auto-tuning
•
Security access
•
Digital inputs for remote profile control
•
Optional relay outputs for events, alarms, or end-of-cycle signal
•
Optional real-time-clock
• Optional RS232/RS422/RS485 MODBUS communications
Theory of Control Operation
The Protocol Plus is a modular microprocessor based digital temperature controller. The
Protocol Plus operates as a dual functioning controller/high limit instrument. The control
portion utilizes a time-proportioning voltage signal to control heating devices with
minimal temperature fluctuations.
The high limit portion protects the product and/or the oven from overheating. If the
product being processed has a critical high temperature limit, the high limit setpoint
should be set to a temperature somewhat below the temperature at which the product
could be damaged. If the product does not have a critical high temperature limit, the
high limit setpoint should be set 5 to 15 degrees higher than the maximum programmed
setpoint at which the oven will operate.