Allen-Bradley 1756-L63XT, User Manual

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162 Rockwell Automation Publication 1756-UM001O-EN-P - October 2014
Chapter 10 Develop Applications
Some object types appear repeatedly, so you have to specify the object name. For
example, there can be several tasks in your application. Each task has its own Task
object that you access by the task name.
There are several objects and attributes that you can use the GSV and SSV
instructions to monitor and set the system. For more information about GSV
instructions, SSV instructions, objects, and attributes see the Logix5000
Controllers General Instructions Reference Manual, publication
1756-RM003 .
Monitoring I/O Connections If communication with a device in the I/O configuration of the controller does
not occur in an application-specific period, the communication times out and the
controller produces warnings.
The minimum timeout period that, once expired without communication, causes
a timeout is 100 ms. The timeout period can be greater, depending on the RPI of
the application. For example, if your application uses the default RPI = 20 ms, the
timeout period is 160 ms.
For more information on how to determine the time for your application, search
the Rockwell Automation Knowledgebase for answer ID 38535. The document
is available at
http://www.rockwellautomation.com/knowledgebase .
When a timeout does occur, the controller produces these warnings;
• An I/O fault status code is indicated on the status display of the 1756-L7 x
controller.
• The I/O status indicator on the front of the 1756-L6x controller flashes
green.
•
A shows over the I/O configuration folder and over the devices that
have timed out.
•
A module fault code is produced, which you can access via the following:
–
The Module Properties dialog box
–
A GSV instruction
For more information about I/O faults, see the Major, Minor, and I/O Faults
Programming Manual, publication
1756-PM014 .
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