Logical Blocks > Device Control function block

Device Control function block parameters

The following table lists the system parameters for the Device Control function block:

Table: Device Control function block system parameters

Parameter

Units

Description

ABNORM_ACTIVE

None

The indication that a block error condition not selected in BAD_MASK (on the function block level) is True (Active) or the indication that an error condition (at the module level) not selected in MERROR_MASK is True (Active) or a module status not selected in MSTATUS_MASK is True (Active).

ACCEPT_D

None

Causes PV_D to become a copy of OUT_D until OUT_D is changed. ACCEPT_D is used to force the block logic to accept the requested state as confirmed without using an actual feedback. The parameter resets when OUT_D changes.

Note

Set this parameter after requesting a new state to simulate the feedback changing to the correct state

BAD_ACTIVE

None

The indication that a block error condition selected in BAD_MASK (at the function block level) is True (Active) or the indication that an error condition (at the module level) selected in MERROR_MASK is True (Active) or a module status selected in MSTATUS_MASK is True (Active).

BAD_MASK

None

The set of active error conditions that triggers a user-defined Bad condition. The user selects a subset of block error (BLOCK_ERR) conditions in the BAD_MASK parameter. When any of these conditions are True, the BAD_ACTIVE parameter becomes True. When any of the BLOCK_ERR conditions that are not included in BAD_MASK are True, ABNORM_ACTIVE becomes True.

BLOCK_ERR

None

The summary of active error conditions associated with the block. The possible block errors for the Device Control function block are:

  • Readback Failed

  • Local Override

  • Output Failure

  • Input Failure/Bad PV

  • Simulate Active

CAS_IN_D

None

The remote discrete setpoint value from another block.

CFM_ACT1_TIME

Seconds

The maximum time allowed to transition to the Active 1 state.

CFM_ACT2_TIME

Seconds

The maximum time allowed to transition to the Active 2 state.

CFM_PASS_TIME

Seconds

The maximum time allowed to transition to the Passive state.

CRACK_TIME

Seconds

The maximum time allowed to drop the confirm PV_D of the previous state.

CRACK_TIMER

Seconds

The elapsed time of the CRACK_TIME setting. When the device cracks or changes state through the FV_D parameter, CRACK_TIMER is held at that value. CRACK_TIMER is reset to zero when SP_D is changed.

DC_STATE

None

The current state of the device controller.

DELAY_TIME

Seconds

Specifies the delay time when SP_D is changed from the Confirmed Passive state to an Active state before the change is sent to DC_STATE logic. This allows a common external setpoint to cause a sequenced start of a group of motors. A change in SP_D to an Active state, when not in the Confirmed Passive state is not delayed.

DELAY_TIMER

Seconds

Elapsed time of DELAY_TIME or RESTART_TIME setting. DELAY_TIMER counts down from DELAY_TIME or RESTART_TIME to zero.

DEVICE_OPTS

None

Device options allow you to select control logic options used in the block. The available options are:
  • Interlock
  • Passive on Active Timeout
  • Passive when Confirmed
  • Permissive
  • Reset Required
  • SP Track
  • Trip

F_IN_D1

None

Current value and status of IO_IN_1.

F_IN_D2

None

Current value and status of IO_IN_2.

F_IN_D3

None

Current value and status of IO_IN_3.

F_IN_D4

None

Current value and status of IO_IN_4.

F_OUT_D1

None

Current value and status of IO_OUT_1.

F_OUT_D2

None

Current value and status of IO_OUT_2.

F_OUT_D3

None

Current value and status of IO_OUT_3.

F_OUT_D4

None

Current value and status of IO_OUT_4.

FAIL

None

Named set that indicates the state of the device controller failure detector. Refer to this function block's Block Execution topic for information on failure codes.

FAIL_ACTIVE

None

Binary indication of an active failure found by the failure detector.

FV_D

None

The feedback state of the discrete device. FV_D represents the state of the field device as determined from state masks for the four discrete inputs when SIMULATE_D is disabled (False).

INSPECT_ACT

None

Indicates if Inspect is enabled and one or more of the limits for the block have been exceeded. The normal value is 0. This parameter is set to 1 only if both of the following conditions are true:
  • The Write to Inspect Alarm context menu item has been selected from Inspect for this block.
  • With the Current Hour filter selected, Inspect indicates that an abnormal condition exists for Mode, Control, Input, or Variability. (Note that an abnormal condition exists for Variability only if both the Variability Index and the Standard Deviation have exceeded their defined limits.)

INTERLOCK_D

None

Discrete input that must be True for OUT_D to remain in an Active state when the Interlock device option is enabled.

INTERLOCK_OPT

None

Interlock device option. Allows you to select the block's behavior when the status of INTERLOCK_D, PERMISSIVE_D, or SHUTDOWN_D is Bad. The three options are: 

  • Always Use Value — The block behaves as described in Block Execution. This is the default value for INTERLOCK_OPT.

  • Use Last Good Value — The block uses the value of each parameter the last time the parameter's status was not Bad. Note that the last good value is not preserved on controller switchover.

  • Passive if Bad — If the status of any of these parameters is Bad, the block uses the passive state value for that parameter, that is, 0 for INTERLOCK_D and PERMISSIVE_D, and 1 for SHUTDOWN_D

IO_IN_1

None

Input hardware reference that defines the Device Signal Tag (DST) for the first I/O channel used for the feedback field measurement.

IO_IN_2

None

Input hardware reference that defines the DST for the second I/O channel used for the feedback field measurement.

IO_IN_3

None

Input hardware reference that defines the DST for the third I/O channel used for the feedback field measurement.

IO_IN_4

None

Input hardware reference that defines the DST for the fourth I/O channel used for the feedback field measurement.

IO_OUT_1

None

Output hardware reference that defines the DST for the first output I/O channel of the block.

IO_OUT_2

None

Output hardware reference that defines the DST for the second output I/O channel of the block.

IO_OUT_3

None

Output hardware reference that defines the DST for the third output I/O channel of the block.

IO_OUT_4

None

Output hardware reference that defines the DST for the fourth output I/O channel of the block.

MODE

None

The mode record of the block. Contains the actual, target, permitted, and normal modes.

OUT_D

None

The discrete output value and status.

PERMISSIVE_D

None

Discrete input that must be True for OUT_D to transition to an Active state when the Permissive device option is set True.

PV_D

None

The discrete process variable used in block execution. It is a copy of FV_D or SP_D.

RESET_D

None

Unlocks the device controller after a failure when the Reset Required device option is enabled. RESET_D unlocks OUT_D from the locked Passive state when Reset Required is enabled.

RESTART_TIME

Seconds

Specifies the delay time when SP_D is changed when the Device Control block is not in the Confirmed Passive state. The value of OUT_D is held at the Passive state while DELAY_TIMER is active. This allows time for a motor to stop before reversing direction, or for a compressor to unload before restarting. A change in SP_D to the Passive state, when not in a Confirmed state, is not delayed.

SHUTDOWN_D

None

Sets and holds OUT_D in the Passive state when SHUTDOWN_D is True.

SIMULATE_D

None

Enables simulation and allows you to enter an FV_D value and status when SIMULATE_IN_D is not connected.

SIMULATE_IN_D

None

The input connector value and status used for FV_D when simulation is enabled.

SP_D

None

The setpoint for the device controller. In Auto mode, SP_D represents the manually entered requested device state. In Cas mode, SP_D comes from the CAS_IN_D input.

STATE_MASKS

None

The command and feedback state definition masks. STATE_MASKS maps combinations of the feedback input signals to the three discrete states and maps each of the three discrete states to combinations of output signals.

TRAVEL_TIMER

Seconds

Counts the elapsed time of travel (the time it took the new requested state to be confirmed). TRAVEL_TIMER is held at the current value when FV_D is changed to the requested state. The timer is reset when the state changes from Confirmed.

Note

TRAVEL_TIMER can be used as a tool to set maximum confirm times.

TRIP_TIME

Seconds

The time allowed before a loss of confirm is interpreted as a trip. For example, when a state was confirmed and the feedback changes state without requesting a new state, the time in TRIP_TIME must pass before the device is labeled Tripped.

TRK_IN_D

None

Discrete input that causes OUT_D to track FV_D. If the SP Track device option is set in DEVICE_OPTS, SP_D also tracks FV_D when TRK_IN_D is 1.

Note

Default values and data type information for the parameters are available by expanding the Parameter View window.