The use case is where we have one measurement for multiple
devices, say 4 for this example. In the field each device is measured for a
time period, let say 4 hours. After these 4 hours the next device is measured.
In PI we have 4 tags, one for each device. In the end result we like to have a
trend with values ONLY for the measured period of the device. The customer does
not want to add tags for this purpose. Also the customer likes to be able to
calculate over the values.
We are thinking to use Abacus for this. We can have the PLC
set a value to the output e.g. -99 when the device is not measured. I looking to REPLACE this -99 values with a STATUS
(e.g. bad value) in Abacus. Here I’m running in to two problems:
- How can I set the status Bad Value?
if ‘tag01’ = -99 then ? else ‘tag01’
- How do replace the value? The above add’s a value
to the history. Event–based does not work as the source tag is the same as the
output. If scheduled and set the output tag to “by –time = Exact time” we get the error
message” “The data method ‘Updatevalue’
is not supported on attribute ‘tag01’”
Guessing the new version of Abacus were you can control the
output write time is helpful, but actually we are looking for a solution before