I/O Blocks > Analog Input (AI) function block

Analog Input function block parameters

The following table lists the system parameters for the Analog Input function block:

Table: Analog Input 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).

ACK_OPTION(1)

None

Enables or disables automatic acknowledgment of fieldbus device alarms associated with Fuji, Endress&Hauser, and Honeywell devices. The default value is 0 (disabled). Set the value of this parameter to 65535 to enable the parameter before downloading the AI block.  (0 = disabled (the default); 65535 = enabled).

ALARM_HYS

Percent or

Percent of PV_SCALE

The amount the alarm value must return within the alarm limit before the associated active alarm condition clears. ALARM_HYS is limited to 50% of scale.

ALERT_KEY(1)

None

A user-assigned identification number reported in alarm messages from the block that allows HMI applications to sort and filter alarms and events. Set this parameter for each function block to indicate the physical unit the function block is associated with. This information can be used in the host for sorting alarms, and so on.

ALM_SEL(1)

None

Used to select the process alarm conditions that cause the OUT_D parameter to be True (Active). 

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 block errors for the Analog Input function block:

  • Out of Service

  • Input Failure/Bad PV

  • Simulate Active (can be set only when the block is downloaded to a controller)

  • Configuration Error

CHANNEL(1)

None

The number of the logical hardware channel that is connected to the I/O block. It defines the transducer to be used going to or from the physical world.

CONDALM_ENABLED(1)

None

Enable and disable conditional alarms.

FIELD_VAL

Percent

The value and status from the I/O card or from the simulated input when simulation is enabled.

HI_ACT

None

The result of alarm detection associated with HI_LIM. If HI_ACT equals True, HI_LIM has been exceeded.

HI_HI_ACT

None

The result of alarm detection associated with HI_HI_LIM. If HI_HI_ACT equals True, HI_HI_LIM has been exceeded.

HI_HI_LIM

EU of PV

The setting for the alarm limit used to detect the high high alarm condition.

HI_HI_PRI(1)

None

To ensure proper operation, do not alter the default value unless instructed to do so by technical support.

HI_LIM

EU of PV

The setting for the alarm limit used to detect the high alarm condition.

HI_PRI(1)

None

To ensure proper operation, do not alter the default value unless instructed to do so by technical support.

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.)

IO_IN

(2)

None

Defines the input DST for the I/O channel used for the PV.

IO_OPTS

None

The supported I/O option for the Analog Input function block is:

  • Low Cutoff

L_TYPE

None

Linearization type. Determines whether the field value is used directly (Direct or Direct Independent), is converted linearly (Indirect), or is converted with the square root (Indirect Square Root).

LO_ACT

None

The result of alarm detection associated with LO_LIM. If LO_ACT equals True, LO_LIM has been exceeded.

LO_LIM

EU of PV

The setting for the alarm limit used to detect the low alarm condition.

LO_LO_ACT

None

The result of alarm detection associated with LO_LO_LIM. If LO_LO_ACT equals True, LO_LO_LIM has been exceeded.

LO_LO_LIM

EU of PV

The setting for the alarm limit used to detect the low low alarm condition.

LO_LO_PRI(1)

None

To ensure proper operation, do not alter the default value unless instructed to do so by technical support.

LO_PR(1)

None

To ensure proper operation, do not alter the default value unless instructed to do so by technical support.

LOW_CUT

EU of PV

Activated when the Low Cutoff I/O option is enabled (True). When the converted measurement is below the LOW_CUT value, the PV is set to 0.0.

MODE

None

Parameter used to request and show the source of the output used by the block.

OUT

EU of OUT_SCALE

The primary value and status calculated by the block in Auto mode. OUT can be set manually in Man mode.

OUT_D(1)

None

The discrete output value and status.

OUT_SCALE

None

The high and low scale values, engineering units code, and number of digits to the right of the decimal point associated with OUT.

PV

EU of OUT

The process variable used in block execution and alarm limit detection.

PV_FTIME

Seconds

The time constant of the first-order PV filter. It is the time required for a 63% change in the FIELD_VAL to be reflected in the PV.

SIMULATE

EU of XD_SCALE

Enables simulation and allows you to enter an input value and status. The SIMULATE value is used by the block only when SIMULATE_IN is not connected.

SIMULATE_IN(2)

EU of XD_SCALE

The input connector value and status used by the block instead of the analog measurement when simulation is enabled. If SIMULATE_IN is connected or has a manually entered value, SIMULATE_IN always overrides SIMULATE.

Note

When SIMULATE_IN is wired from an input source on the function block diagram, it always overrides a manually entered value.

ST_REV(1)

None

The revision level of the static data associated with the function block. To support tracking changes in static parameter fields, the associated block's static revision parameter is incremented each time a static parameter field value is changed. Also, the associated block's static revision parameter is incremented if a static parameter field is written but the value is not changed.

STATUS_OPTS

None

Use this parameter to set how status is handled and processed. When the block is assigned to a controller, the available status options are:

  • Uncertain if Man mode

  • Bad if Limited

  • Uncertain if Limited

When the block is assigned to a fieldbus device, the available options are:

  • Uncertain if Man mode

  • Bad if Limited

  • Uncertain if Limited

  • Propagate Fault Forward

STDEV

EU of OUT_SCALE or EU of PV_SCALE

The standard deviation of PV. For analog control blocks in AUTO, mean is assumed to be the SP.  

STDEV_CAP

EU of OUT_SCALE or EU of PV_SCALE

(reports in percent to Inspect)

The estimated capability standard deviation (measurement of short term variation). An estimate of the least standard deviation the process could achieve ideally.

STDEV_TIME(2)

Seconds

(reports in percent to Inspect)

The time frame over which STDEV and STDEV_CAP are performed. The default value of zero is good for most processes where the scan rate is no more than approximately 10 times faster than the time to steady state.

If the process is relatively much slower, it is recommended that you enter the approximate time it takes for the process to return to steady state after a change. This ensures that the STDEV and STDEV_CAP calculations accurately consider the actual time constant of the process.

STRATEGY(1)

None

Used to identify groupings of blocks. This data is not checked or processed by the block.

SUBSTITUTE_IN(1)

Determined by source or EU of PV_SCALE

If there is a problem communicating with the field device and SUBSTITUTE_IN has a non-Bad status, the controller passes the SUBSTITUTE_IN value through to the output parameter(s) of the shadow block.

XD_SCALE

None

The high and low scale values, engineering units code, and number of digits to the right of the decimal point associated with the channel input value.

(1) These parameters are only visible in one or more of the extended versions of this block.
(2) These parameters may not be visible in certain extended versions of the block.
Note

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