Allen-Bradley 1756-L6 Series, Справочное руководство, Страница: 88 / 134

88 Rockwell Automation Publication 1756-RM001I-EN-P - May 2012
Chapter 8 Faults in the ControlLogix System
Module Fault Reporting for
Any ControlLogix or FLEX I/O
Module You must verify that all components in the system are operating properly. This
can be accomplished in ladder logic through the use of the Get System Value
instruction (GSV) and an examination of the MODULE Object’s Entry Status’
attribute for a running condition.
An example of how this might be done is shown in Figure 48 . This method, or
something similar, must be used to interrogate the health of each I/O module in
the system.
Figure 48 - Example of Checking a Module’s Health in Ladder Logic
For more information on the GSV instruction, monitor the SlotStatusBits for the
Input tag of the associated adapter. The lower 8 bits of this tag correspond to the
associated slot. For example, the tag “Node3:I.Slot1StatusBits” is defined as
follows:
• Node 3 is the name given to the adapter, in this example, a 1794-
ACNR15.
• I indicates the Input file.
• SlotStatusBits is a 32-bit value, where the lower 8 bits correspond to a
FLEX I/O module, as shown.
Checking Keyswitch Position
with GSV Instruction The following rungs generate a fault if the keyswitch on the front of the
controller is switched from the RUN position.
Figure 49 - Keyswitch State (Operation Mode) Change Logic
GSV
Obtain MODULE Object’s
Entry Status
AND
Mask Off Lower 12 Bits
of Value
NEQ
Check Entry Status to
make sure module is
running.
Fault
Module 7 Module 6 Module 5 Module 4 Module 3 Module 2 Module 1 Module 0
Alarm to Operator
KEYSTATE.13
GSV
Class: CONTROLLERDEVICE
Attribute: STATUS
Destination: KEYSTATE
Fault
Fault