Protege System Controller Reference Manual

Register Offset
Register Function
8 Stage 1 Demand Value
The stage one demand value is the amount of plant error that is required to activate the
first stage of cooling or heating. Plant error is calculated using a custom PI loop. The
error is accumulated using the settings for the Integral Value and Hysteresis Settings. The
error value is the difference between the set point and the current space temperature
with the addition of the accumulated error.
9 Stage 2 Demand Value
The stage two demand value is the amount of plant error that is required to activate the
second stage of cooling or heating.
10 Stage 3 Demand Value
The stage three demand value is the amount of plant error that is required to activate the
third stage of cooling or heating.
11 Stage 4 Demand Value
12 Current RTHP Mode
13 Current Plant Error
14 Integral Error
15 Integral Term
16 Output Error
17 Integral Gain
The stage four demand value is the amount of plant error that is required to activate the
fourth stage of cooling or heating.
The current mode that the RTHP is operating in. The RTHP modes are listed in the
section below.
The current plant error is the error in the temperature value difference between the set
point and the current temperature. This value is for display only and used to calculate the
drive required for the RTHP to obtain the desired set point.
The integral error is the amount of raw calculated error using the integral portion of the PI
loop used for the control of the RTHP unit and is calculated ONLY in a cooling or heating
requirement mode.
The integral term is the result of a calculation using the integral gain and the integral error
to obtain a value that can be used to add with the Plant Error to ensure that the heating
and cooling set points are meet with the maximum amount of efficiency.
The output error is the absolute output error at the current point and can be used as a
guide when tuning the RTHP. The output error represents the Integral Term added with
the raw Plant Error values. The output error is used to calculate the staging of the heating
and cooling within the RTHP unit.
The integral gain is the gain of the integral portion of the PI loop and is a division of the
actual integral error amount that is used to form the calculation. The integral gain will
divide by 1, 2, 4, 8 etc by setting a value of 1,2,3,4 ... 15.
If a value of 0 is programmed for the integral gain the system will not use integral
within the PI loop and it will be disabled.
18 Integral Maximum Value
As the integral value is a calculated value that is continually updated it can easily reach a
saturation point where the plant can not meet the integral and plant error values. In this
case we program a limit that will stop the integral from increasing beyond a recoverable
point.
PRT-CTRL-SE Protege System Controller Reference Manual | PRT-CTRL-SE 229