Cycler Function Block

The Cycler function is a generic stage driver or a Thermostat Stage Cycler dependant on the value of the CPH parameter (CPH=0 means stager functionality, and CPH=1-60 gives thermostat 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/1.2.

Figure 1: Cycler Function Block

Figure 2: Cycler Property Sheet

Figure 3: Cycler Behaviour Diagram

Input

Input Name

Description

In

Input load demand in percentage.

Numeric: 32-Bit Floating value -100-100. Default: Null

MaxStg

Maximum stages available to be turned on.

Numeric: 32-Bit Integer value 1-25. Default: Null

MinOn

Minimum time a stage should be turned on in Sec.

Numeric: 32-Bit Integer value 0-64799. Default: Null

MinOff

Minimum time a stage should be turned off in Sec.

Numeric: 32-Bit Integer value 0-64799. Default: Null

InterStageOn

Minimum time before the next stage can be turned on in Sec.

Numeric: 32-Bit Integer value 0-64799. Default: Null

InterStageOff

Minimum time before the next stage can be turned off in Sec.

Numeric: 32-Bit Integer value 0-64799. Default: Null

OverrideOff

Override to turn off stages.

Numeric: Binary value 0, 1. Default: Null

Disable

Disable function.

Numeric: Binary value 0, 1. Default: Null

Table 1: Inputs of Cycler Function

Output

Output Name

Description

Stages

The Number of stages active.

Table 2: Outputs of Cycler Function

Parameter

Parameter Name

Description

In Par

Input load demand in percentage.

Numeric: 32-Bit Floating value -100-100. Default: Null

MaxStg Par

Maximum stages available to be turned on.

Numeric: 32-Bit Integer value 1-25. Default: Null

MinOn Par

Minimum time a stage should be turned on in Sec.

Numeric: 32-Bit Integer value 0-64799. Default: Null

MinOff Par

Minimum time a stage should be turned off in Sec.

Numeric: 32-Bit Integer value 0-64799. Default: Null

InterStageOn Par

Minimum time before the next stage can be turned on in Sec.

Numeric: 32-Bit Integer value 0-64799. Default: Null

InterStageOff Par

Minimum time before the next stage can be turned off in Sec.

Numeric: 32-Bit Integer value 0-64799. Default: Null

AnticipatorAuthority

Helps in adjusting cycler behaviour in percentage.

Numeric: 32-Bit Floating value 0-200. Default: 100

CPH

Cycles per hour.

CPH (non-zero) is the max cycle rate in CPH when input is halfway between the stages available, and AnticAuth is at the default value (100 %). CPH = 0 means the Stager logic is performed and has no other effect

Numeric: 32-Bit Integer value 0-60. Default: 3

Hysteresis

Stage off hysteresis.

Numeric: 32-Bit Floating value 0-100. Default: 0

Out Save

Master Sync Enabled : If you set it to "true" the last output will be set as output for one cycle after the controller restarts. The application can use it to return to the same state before the controller restart.

Stage: To enable or disable the Stage feature.

Table 3: Parameter of Cycler Function

Examples

  1. The below screenshot explains how the stages become ON when MaxStg =1, interstage delay On /Off = 10 sec, Hysteresis = 10, AnticAuth = 100, CPH = 0. CPH = 0 means the Stager logic is performed. For screen shot refer an example of the Stager Block.

  2. 1-Stage Example

    The below screenshot explains how the single stage becomes ON when MaxStg =1, interstage delay On/Off = 5 sec, Hysteresis = 5, AnticAuth = 100, CPH = 3 i.e. Cooling.

    Stage 1 On = 25%, which is (AnticAuth/MaxStg)-Hysteresis

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

    For turning off stage N the criterion is:

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

    The below screenshot explains how the single stage becomes OFF when MaxStg =1, interstage delay On/Off = 5 sec, Hysteresis = 5, AnticAuth = 100, CPH = 3 i.e. Cooling.

    Stage 1 On = 15%, which is (AnticAuth/MaxStgs)-Hysteresis

  3. 2-Stage Example

    The below screenshot explains how the 2 stage becomes ON when MaxStg =2, interstage delay On/Off = 5 sec, Hysteresis = 5, AnticAuth = 100, CPH = 3 i.e. Cooling.

    Stage 1 On = 30%, which is (AnticAuth/MaxStgs)-Hysteresis

    Stage 2 On = 35%, which is (AnticAuth/MaxStgs)-Hysteresis

    The below screenshot explains how the dual stages becomes OFF when MaxStg =2, interstage delay On/Off = 5 sec, Hysteresis = 5, AnticAuth = 100, CPH = 3 i.e. Cooling.

    Stage 1 On = 32%, which is (AnticAuth/MaxStgs)-Hysteresis

    Stage 2 On = 30%, which is (AnticAuth/MaxStgs)-Hysteresis

    This behavior can be visualized with a 2 stage example below, where, as the load slowly increases,the first stage starts with a low cycle rate and low average on-time, and as the load increases the cycle rate increases to a max at 50% average on-time, and decreases again as the average on-time approaches 100% until the first stage is now locked on and the second stage then follows the same pattern.

  4. The below screenshot explains how 4 are overridden by the Override Off Pushbutton

    When MaxStg = 4, interstage delay On/Off = 3 sec, MinOn/MinOff = 5, Hysteresis = 10, AnticAuth = 100, CPH = 3 i.e. Cooling, OverrideOff = "true".

    When override is "true" active stages are shed (turned off) based on MinOn and interstage timers regardless of the CmdPercent input. Output is number of stages active (0- MaxStgs) which can be sent to the StageDriver function block.

    Stage 1,2,3 &4 are OFF = 0%, which is (AnticAuth/MaxStgs)-Hysteresis

  5. The below screenshot explains how the 4 stages are overridden by OverrideOff Pushbutton.

    When MaxStg = 4, interstage delay On/Off = 3 sec, MinOn/MinOff = 5, Hysteresis = 10, AnticAuth = 100, CPH = 3 i.e. Cooling, OverrideOff = "true".

    Stage 1,2,3 &4 are OFF = 0%, which is (AnticAuth/MaxStgs)-Hysteresis

  6. 4- Stage Example

    The below screenshot explains how the 4 stages are increasing based on the command percent.

    When MaxStg = 4, interstage delay On/Off = 3 sec, MinOn/MinOff = 2 sec, Hysteresis = 10,AnticAuth = 100, CPH = 60, OverrideOff = "false".

    Stage 1,2,3 &4 are OFF = 100%, which is (AnticAuth/MaxStgs)-Hysteresis

Refer to General Description for general information about IRM N4 Function Blocks.