How to make a LimitArray for use in High Performance Trend
I want to include a trend on a faceplate for an analog input containing 6 alarm levels. For that purpose I'm considereing the High Performance Trend which can take an array of alarm limits defined in a LimitArray Type. My question is:
How do a convert my alarm limits (real) to a LimitArray?
I found very little help in the System 800xA Engineering Process Graphics (document number 3BSE049230-510 E) but I understand that it includes at least some information about coloring of the limits on the trend.
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Its a bit of a pain but see Table 59 for a description of the LimitValueType. You need to construct a "Limit" expression to construct LimitValueTypes and then pack then into a LimitArray.
You will end up with a nested expression. The expression builder will help you to get the syntax right, but it should look something like .....
LimitArray ( Limit ( <Value>, <limit type>, <pen>, <brush> ), Limit ( <Value>, <limit type>, <pen>, <brush> ) .... etc )
In turn, <Pen> and <brush> can be expressions. See tables 55 and 56
"Value" is the limit value and LimitType is (I beleive) H, HH, L , LL etc but you will need to experiment to see what the exact syntax should be.