Cycler

The function block has the following input pins in, disable, overrideoff and the output of the number of stages turned on is provided by Stages_Active. This function is a generic stage driver or a Thermostat Stage Cycler dependant on the value of the CPH parameter.

Logic Inputs

Input Name Input Value Logic Value Description
disable unconnected 0 Normal operation
  VAL != 0.0 1 Disable block, output = 0
  0 0 Normal operation
  invalid 0 Normal operation
overrideOff unconnected 0 Normal operation
  VAL != 0.0 1 Turns off stages as min on time allows.
  0 0 Normal operation
  invalid 0 Normal operation

Analog Inputs

Range
Input Name Low High Input Value Description
in 0 100 Unconnected stgsAct = 0
(%) invalid in = 0%
maxStgs 1 255 unconnected stgsAct = 0
invalid maxstgs = 1
minOn 0 64799 unconnected stgsAct = 0
(sec) invalid stgsAct = 0
minOff 0 64799 unconnected stgsAct = 0
(sec) invalid stgsAct = 0
instgOn 0 64799 unconnected stgsAct = 0
(sec) invalid stgsAct = 0
instgOff 0 64799 unconnected stgsAct = 0
(sec) invalid stgsAct = 0

Output

Output Name Range Description
STAGES_ACTIVE 0 to +100 % The number of stages active (on)

Setpoints

Name Range/Value Description
anticipatorAuthority 0 to 200% User specified value. Typical value is 100%
cph 1 to 60 User specified value.
hyst 0 to 100 User specified value.

Configuration

  1. Specify CPH from 1 to 60.
  2. Specify Anticipator Authority from 0 to 200 %. Typical value is 100%.
  3. Specify hysteresis from 0 to 100.

Cycler Functionality

The Cycler function is the traditional anticipator cycling algorithm used in Honeywell thermostats. Input is ether P or PI space temperature error in % (0-100). Standard (recommended) settings are cph=3 for cooling, cph = 6 for heating, anticAuth = 100%, hyst = 100%/maxstages/2. Also, for multiple stage cyclers the PID block feeding this block should have an appropriately large throttling range to achieve smooth behavior.

cycler1.gif (6109 bytes)

Stager Functionality

The Stager Function takes a 0-100 percent (typically PID error) input and determines how many stages to turn on. The 0-100 percent input range is divided evenly between how many stages are configured in MaxStages. The first stage is turned on at CmdPercent > 0 and off at CmdPercent < - Hyst. As shown in following illustration the general criterion for turning on stage N is:

CmdPercent > (N -1)*100%/MaxStages.

For turning off stage N the criterion is:

CmdPercent < (N -1)*100%/MaxStages - Hyst.

From iteration to iteration, the Function Block keeps track of the on timer, off timer, anticipator, and CPH multiplier. On power up/reset, the off timer and anticipator are cleared, the on timer is set equal to the inter-stage on time and the CPH multiplier is recalculated.

cycler2.gif (4814 bytes)

When override is true, active stages are shed (turned off) based on min on and interstage timers regardless of the CmdPercent input. Output is number of stages active (0-MaxStages) which can be sent to the StageDriver function block. Configuration parameters include: