Ratio function block parameters

None

The indication that a block error condition not selected in BAD_MASK (on the function block level) is True (Active).

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.

None

The indication that a block error condition selected in BAD_MASK (at the function block level) is True (Active).

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.

Seconds

Specifies the time for dissipation of the internal balancing bias.

EU of OUT_SCALE

The analog input value and status from another block's BKCAL_OUT output that is used by an upstream block for bumpless transfer.

EU of PV_SCALE

The value and status required by the BKCAL_IN input of another block to prevent reset windup and provide bumpless transfer to closed loop control.

None

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

• Out of Service

• Local Override

• Input Failure/Bad PV

EU of PV_SCALE

The remote setpoint value from another block.

None

Control options allow you to specify control strategy options. The valid control options are:

• No OUT Limits in Manual

• Obey SP lim if Cas or RCas

• Use BKCAL_OUT With IN_1

• Act on IR

• Use PV for BKCAL_OUT

• Track in Manual

• Track Enable

• SP Track Retained Target

• SP-PV Track in LO or IMan

• SP-PV Track in Man.

None

The result of alarm detection associated with DV_HI_LIM. If DV_HI_ACT equals True, DV_HI_LIM has been exceeded.

EU of PV_SCALE

The amount by which PV can deviate above SP before the deviation high alarm is triggered. The magnitude of DV_HI_LIM cannot be greater than the range of PV_SCALE. When this limit is exceeded, DV_HI_ACT is set to True. The deviation of PV is above SP.

None

The result of alarm detection associated with DV_LO_LIM. If DV_LO_ACT equals True, DV_LO_LIM has been exceeded.

EU of PV_SCALE

The amount by which PV can deviate below SP before the deviation low alarm is triggered. The magnitude of DV_LO_LIM cannot be greater than the range of PV_SCALE. When this limit is exceeded, DV_LO_ACT is set to True. Note that DV_LO_LIM is a negative number and is compared against PV – SP.

None

The FRSI add-on I/O option supported is Treat_IN_1 as wild.

None

The multiplier used to scale the ratio value.

None

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

None

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

EU of PV_SCALE

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

EU of PV_SCALE

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

Defined by supplying block

The analog input value and status used with IN_1 to calculate PV.

Defined by supplying block

The analog input value and status used to calculate OUT.

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.)

None

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

EU of PV_SCALE

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

None

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

EU of PV_SCALE

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

None

Parameter used to request, show, and set the block operating state.

EU of OUT_SCALE

The analog output value and status.

EU of OUT_SCALE

The maximum output value allowed.

EU of OUT_SCALE

The minimum output value allowed.

None

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

EU of PV_SCALE

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

Seconds

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

None

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

Seconds

The time constant of the first-order ratio filter applied to IN_1. It is the time required for a 63% change in IN_1.

EU of SP_SCALE

The remote analog setpoint value and status. Input provided by a device or the output of another block.

EU of PV_SCALE

The output provided for bumpless mode transfer and reset limiting by the source of RCAS_IN. Essentially the equivalent of BKCAL_OUT for RCAS_IN.

None

Defines action to be taken on remote control device time out.

Seconds

The maximum allowable time between RCAS_IN and ROUT_IN updates. If exceeded, mode shedding takes place.

EU of PV_SCALE

The block's setpoint value.

EU of PV_SCALE

The highest setpoint value allowed.

EU of PV_SCALE

The lowest setpoint value allowed.

EU of PV_SCALE per second

Ramp rate at which downward setpoint changes are acted on in Auto mode, in PV units per second. If the ramp rate is set to 0.0, then the setpoint is used immediately. For control blocks, rate limiting applies only in Auto. For output blocks, rate limiting applies in Auto, Cas, and RCas modes.

EU of PV_SCALE per second

Ramp rate at which upward setpoint changes are acted on in Auto mode, in PV units per second. If the ramp rate is set to 0.0, then the setpoint is used immediately. For control blocks, rate limiting applies only in Auto. For output blocks, rate limiting applies in Auto, Cas, and RCas modes.

EU of PV_SCALE

The working setpoint of the block. It is the result of setpoint limiting and setpoint rate of change limiting.

None

Status options allow you to select options for status handling and processing. The supported status options are:

• Target to Manual if Bad IN

• Use Uncertain as Good

• IFS if Bad CAS_IN

• IFS if Bad IN.

EU of OUT_SCALE or EU of PV_SCALE

(reports in percent to Inspect)

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

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.

Seconds

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.

None

Discrete input that initiates the external tracking function.

None

The high and low scale values, engineering units code, and number of digits to the right of the decimal point associated with the external tracking value (TRK_VAL).

EU of TRK_SCALE

The analog input used in the external tracking function.