Rockwell Automation Publication 1756-UM540E-EN-P - December 2017 105
1756-OF8I Isolated Analog Output Module Chapter 5
Response Times for Output Modules
Response time to a change in ownership is from the time the event takes place
until the time that the output modules uses the connection data from the
redundant connection.
Digital output response to a change in ownership in less than 250 ms. The
average time is 220 ms. A faster RPI does not increase the response time. We
recommend a digital output RPI of 25 ms.
These recommendations are for response performance:
• Faster RPIs have a longer response time.
• Slower RPIs can have a much longer response time.
• RPIs should be 4 x RPI = 200 ms, 8 x RPI = 200 ms, or
16 x RPI = 200 ms, so 25 is the recommended RPI.
• If the prior RPI criterion is not met, the CIP connection timeout delay
minimum will be 200 ms + 1 RPI. If the 4/8/16 x RPI does not equal 200
ms (or 100 ms), then the response will be longer.
• For non-redundant ControlLogix applications, the CIP connection
timeout delay minimum is 100 ms.
• Slower RPIs greatly limit the effect of the response time on the application.
IMPORTANT This information pertains only to output modules.
Use existing guidelines for setting input module RPIs.
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