FC 139 - Passive Station Interface

The passive station interface function code emulates a control station using boolean and real inputs. Each passive station interface block links to an associated station block (function code 80). Specification S16 of the station block must be set to 254. This value defines a passive station interface.

 

 

Outputs:

Blk

Type

Description

N

B

Auto bypass request

N+1

B

Reserved

N+2

B

Reserved

N+3

B

Reserved

N+4

B

Reserved

 

 

 

Specifications:

Spec

Tune

Default

Type

Range

Description

S1

N

0

I

Note 1

Block address of station block (function code 80)

S2

N

0

I

Note 1

Block address of set point raise

S3

N

0

I

Note 1

Block address of set point lower

S4

N

0

I

Note 1

Block address of control output raise

S5

N

0

I

Note 1

Block address of control output lower

S6

N

1

I

Note 1

Block address of auto/manual permissive

S7

N

0

I

Note 1

Block address of auto/manual transfer

S8

N

0

I

Note 1

Block address of manual bypass request

S9

N

5

I

Note 1

Block address of bypass control output

S10

N

0

I

Full

Check input quality:

0 = disable

1 = enable

S11

Y

2.500

R

Full

Set point ramp rate (units/sec)

S12

Y

2.500

R

Full

Control output ramp rate (units/sec)

S13

N

1

I

Full

Bad quality bypass control output option:

0 = prevent bypass exit

1 = permit bypass exit

S14

N

5

I

Note 1

Spare real input

S15

Y

1.000

R

Full

Maximum rate of change in bypass control output (units)

S16

N

5

I

Note 1

Spare real input

S17

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

 

 

139.1   Explanation

 

 

139.1.1   Specifications

 

S1

Block address of the station block (function code 80). Specification S16 of the station block must be set to 254. This value defines a passive station interface.

 

S2

Block address of set point raise. This input can simulate set point ramping. Specification S11 adjusts the set point ramp rate.

 

S3

Block address of set point lower. This input can simulate set point ramping. Specification S11 adjusts the set point ramp rate.

 

S4

Block address of control output raise. This input can simulate control output ramping. Specification S12 adjusts the control output ramp rate.

 

S5

Block address of control output lower. This input can simulate control output ramping. Specification S12 adjusts the control output ramp rate.

 

S6

Block address of auto/manual permissive. A mode change is possible when this input is active (logic 1). Refer to S7.

 

S7

Block address of the auto/manual transfer. A zero to one transition on this input will cause a mode change (auto/manual) if S6 is active.

 

S8

Block address of the manual bypass request. The station is put in bypass when this input is active (logic 1).

 

S9

Block address of the bypass control output. This input allows the aligning of the station output to the actual output (in

bypass).

 

NOTES:

  1. The BRC-100 controller will enter the error mode when S13 equals zero and S9 references a block output that does not have a defined quality status.

  2. The station will always enter auto bypass when the quality of the associated analog output defined by S28 of function code 80 is bad.

 

S10

Enables input quality checking:

0 = disable input quality checking

1 = enable input quality checking

 

NOTE: The station enters auto bypass when an input of function code 139 has bad quality when S10 equals one.

 

S11

Controls the set point ramp rate. The rate is expressed in units per second.

 

S12

Determines the control output ramp rate. The rate is expressed in units per second.

 

S13

Bad quality bypass control output option.

0 = bypass exiting not permitted when <S9> has bad quality

1 = bypass exiting always permitted

 

S14

Spare real input.

 

S15

Maximum change in the bypass control output input <S9> that is allowed for exiting bypass. This specification is only in effect while the station is in auto bypass. The station will be prevented from exiting auto bypass if the change in the <S9> input from one segment cycle execution to the next is greater than this value. To derive the S15 value from a rate of change value, use the formula:

 

FC139 S15 setting = rate of change (units/sec or units/min) x S2 of FC82

 

The <S9> input is typically connected to a feedback from the control output of the station block (function code 80). When this is the case, the use of this specification allows the station to maintain itself in the bypass condition until it is detected that the control output is not changing rapidly. The use of this specification prevents the auto bypass output from switching control of the control output analog output signal back to the AOT, CIO, CIS, or ASO hardware while the control output is changing.

 

S16 and S17

Spare real and boolean inputs respectively.

 

 

139.1.2  Outputs

 

N

(Auto bypass request) This boolean output signals auto bypass when active (logic 1).

 

N+1 through N+4

Reserved.

 

 

139.2   Application

 

 

Figure 139-1 shows a configuration using the passive station interface block. This example allows simultaneous control of a station function from both a console and external pushbuttons. A hard station cannot be used with this configuration.

 

NOTE: The inputs to the passive station interface do not have to come from external inputs. Internal logic can generate these inputs. For example, the auto permissive could be generated from logic that only allows automatic during certain portions of the process operation.