Omron DR 170 14 - Manual (Page 30)

Klinkmann Automation Omron Ethernet DAServer 28
Omron Ethernet DAServer Ver 1.x User Manual Rev 1.3 17014m13
To edit update intervals
• To edit the update interval for an object, double-click its value in the Update Interval
column and make the edit.
• Update Interval is the frequency (in milliseconds) that the DAServer acquires data from
the topics associated with that device group.
• Different topics can be polled at different rates in a PLC by defining multiple device-
group names for the same PLC and setting a different Update Interval for each device
group.
Note: When you select another part of the Omron Ethernet DAServer tree hierarchy, you
are prompted to save the modifications to the configuration set.
Scan-Based Message Handling
DAServers are based on the concept of polling a hardware device for information. This
polling is driven by a need which is expressed in the form of requests from one or more
clients. Once a particular piece of information has been requested by a client, the
DAServer formulates its own request and sends that request to the hardware device. The
DAServer then waits for a response to its request. Once the information has been
received, the DAServer passes that information back to the client, and repeats the
process until all clients have ceased requesting information.
The rate at which the DAServer will poll a particular device for a specific piece of
information is defined in the device group (topic definition) inside the DAServer, using a
parameter called the Update Interval. When setting this parameter, there is always a
trade-off between the update speed of the device group and the resulting decrease in
system responsiveness.
Since you more than likely want very fast response, the temptation is to set the Update
Interval to a value close to 0 seconds. However, if every point is polled at this rate, the
entire system will suffer due to slow response time. Therefore, you should compromise,
and set the Update Interval to a more reasonable value. You could also create multiple
device groups for each device, setting the Update Interval to different values, then
assigning different items to different device groups depending on how quickly the values
change and how quickly you want to see an update of those changes.
Some items, like alarms, change very infrequently but because of their importance
require very fast updates. For those kinds of items, you should set the Update Interval at
a very small value. If you desire an immediate response, set the Update Interval at 1.
Archiving Configuration Sets
After you have configured your DAServer, you can archive that specific configuration. You
can archive more than one configuration set, and subsequently choose different
configurations for different purposes.
To archive configuration sets
1. In the DAServer Manager, right-click on the Configuration node in the hierarchy below
your DAServer.
2. Select Archive Configuration Set from the shortcut menu.