4

Example

In the following example, when %M00035 is on, the input and output copies are disabled.

%M00035

 

 

 

 

 

 

 

 

%T00041

 

MOVE_

 

 

MOVE_

 

 

SVC_

 

INT

 

 

 

INT

 

 

 

REQ

CONST

IN

Q

%L00001

CONST

IN

Q

%L00002

CONST

FNC

00000

LEN

 

 

00001

LEN

 

 

00043

 

 

 

 

 

 

 

 

 

 

00001

 

 

00001

 

%L00001

PARM

Backup Qualification with SVCREQ #43

Service Request function block #43 can be used to help determine if the backup PLC unit is collecting inputs properly (that is, validate the input scan). It can also be used to help determine whether the backup PLC unit is calculating outputs and internal variables properly (that is, validate the logic solution). Instructions are given below.

Validating the Backup PLC's Input Scan

To determine whether the backup PLC is collecting inputs properly, follow these steps:

1.Activate SVCREQ #43 on the backup CPU, passing “0, 1" to disable the input and output data transfer copies.

2.Observe the backup unit's %I and %AI reference tables. The values in these tables correspond to the inputs that the backup is currently collecting.

3.Visually compare the backup unit's %I and %AI reference tables with the active unit's tables. Pay special attention to the %I and %AI references that are configured to be shared between the two units.

4.When you are satisfied that the backup unit is collecting inputs properly, disable the rung that calls SVCREQ #43.

Validating the Backup PLC's Logic Solution

To determine whether the backup PLC is calculating outputs and internal variables properly, follow these steps:

1.Activate SVCREQ #43 on the backup CPU, passing “0, 2" to disable the output data transfer copy.

2.Observe the backup unit's %Q, %AQ, %M, and %R reference tables. The values in these tables correspond to the inputs that the backup is currently calculating.

3.Visually compare the backup unit's %Q, %AQ, %M, and %R reference tables with the active unit's tables. Pay special attention to the %Q, %AQ, %M, and %R references that are configured to be shared between the two units.

4.When you are satisfied that the backup unit is calculating outputs and internal variables properly, disable the rung that calls SVCREQ #43.

GFK-1527A

Chapter 4 Normal Operation

4-13

Page 52
Image 52
GE 90-70 manual Backup Qualification with Svcreq #43, Validating the Backup PLCs Input Scan