FC 145 - Frequency Counter / Slave

The frequency counter/slave function code interfaces the frequency counter slave to a multifunction controller or multifunction processor. Output N provides the frequency in hertz times the gain (S5). The quality and alarms on this output reflect the current state of the block. This includes the rate alarms and the high and low rate alarms. The high and low rate alarms display on operator devices as HD and LD respectively. The high and low alarms and quality are included in the frequency output N. These alarms can be detected using the test alarm function (function code 69).

 

Quality is detected using the test quality function (function code 31). High rate of change occurs when the frequency output N changes in a positive direction from the previous output in excess of S9. Low rate of change occurs when the frequency output has changed in a negative direction from the previous output in excess of S9. The configurable high and low alarm limits (S6 and S7) determine when the alarm outputs N+1 and N+2 are set. To prevent alarm chatter, the alarm deadband (S8), expressed in engineering units, is provided for S6 and S7. The last output N+3 reports the status of I/O module communications.

 

The IMFCS01 module typically measures rotational speed of a turbine utilizing a toothed wheel attached to the shaft and a magnetic pickup.

 

 

 

Outputs:

Blk

Type

Description

N

R

Frequency (hertz)  gain (with alarms)

N+1

B

High alarm:

0 = good

1 = alarm

N+2

B

Low alarm:

0 = good

1 = alarm

N+3

B

I/O module communication:

0 = good

1 = bad

 

 

 

Specifications:

Spec

Tune

Default

Type

Range

Description

S1

N

0

I

0 - 63

Expander bus address I/O module

S2

N

0

I

Full

Spare

S3

N

0

I

Full

Spare

S4

N

0

I

Full

Spare boolean input

S5

Y

1.000

R

Full

Engineering Unit Gain

S6

Y

9.2E18

R

Full

Engineering Unit High Alarm

S7

Y

-9.2E18

R

Full

Engineering Unit Low Alarm

S8

Y

0.000

R

Full

Absolute Alarm Deadband

S9

Y

9.2E18

R

Full

Engineering Unit Rate of Change Alarm

S10

N

0

I

Note 1

Spare Boolean Input

 

NOTES:

1. Maximum values are: 9,998 for the BRC-100, IMMFP11/12 and 31,998 for the HAC