Protege System Controller Reference Manual

Register Offset
Register Function
1 Input Hysterisis Value
2 Input Hysterisis Time
The hysterisis value that the comparison input must be above or below the setpoint to
activate the low or high PGM outputs. This value is added to the input value or
subtracted dependent on the direction the comparison input is changing.
The time that the value must be above or below the set point to proceed with activating
the low and high PGM outputs. This setting is the number of seconds the value must be
above or below.
Using the register configuration settings above and the following data values in the configuration registers the
following will be observed. The comparison input register in this example is linked to the first channel on the
Analog Expander. This was tested using a linear variable resistor with a 10V supply reference that can be
connected to the input to allow manual control using the knob on the variable resistor.
Programmed Settings
Base Register is 00100
Value Data Register is 00000 (First Analog Input Channel on AE001)
Base Register Configuration
Register 00100 Input Set Point = 1200
Register 00101 Input Hysterisis = 100
Register 00102 Input Hysterisis Time = 20
Given the above settings and assuming that the data value for the input comparison is set to 0 when the
programmable function is started after 20 seconds the low PGM (if it is set) will be activated. When the data
value rises and exceeds the 1200 set point for longer than 20 seconds (Hysterisis Time) the low value will be
deactivated. If the input then exceeds the set point plus the hysterisis value (1300) for longer than 20 seconds
the high PGM will be activated and will deactivate when the input value is below the set point for longer than the
20 second time.
Setting a very low hysterisis time value can result in the system oscillating and causing unstable operation, it is
recommended to have a reasonable value for these settings.
Daylight Sensor
For example a daylight sensor that can be used would be set to hysterisis of 250 and a time of 120 seconds,
this ensures any variation in cloud cover, headlights or other scenarios are managed by the comparison function
and would not cause the lights being controlled from either flicking off or on in a brief over/under light situation.
Comparison Input Register
The comparison input register is used for the source of the data to perform a comparison. For example using a
register setting of 00000 would perform a comparison with the data being sent from Channel 1 of the first
Analog Expander.
i
The comparison input register DOES NOT have to be a register that is linked with an analog expander.
This can be a register that is controlled from the Protege System Management Suite or from another
register. This is also an ideal method of testing the comparison function before putting it in to
operation.
PRT-CTRL-SE Protege System Controller Reference Manual | PRT-CTRL-SE 239