Siemens SITRANS LG250 Operating Instructions Manual page 46

is required. If a function test is necessary, the following message is
displayed.
In this case, you have to carry out a function test.
Function test
During a function test, you have to test the safety function of the
instrument in the vessel with the original medium.
You can find the detailed sequence of the function test in chapter
"Functional safety (SIL)"
For this purpose, you should know the filling height of the vessel as
well as the min. and max. levels respectively for 4 and 20 mA. You
then can calculate the respective output current.
Measure the output current of SITRANS LG250 with a suitable multi-
meter and compare the measured output current with the calculated
output current.
You have to determine the permissible deviation of the values
yourself. This deviation depends on the the accuracy requirements of
your measurement loop. Determine the permissible tolerance for the
deviation.
If you have to interrupt the function, you can leave the SITRANS
LG250 in the respective situation.
As long as SITRANS LG250 is powered, the display and adjustment
module remains in the currently set adjustment menu.
To interrupt the function test, you have to push the button "ESC".
If you carry out the function test by means of the "PACTware" soft-
ware, you can store the previously performed tests and continue from
there later on.
Verify parameter
All safety-relevant parameters must be verified after a change. After
the function test, all modified, safety-relevant parameters will be
listed. Confirm the modified values one after the other.
If the described process of parameter adjustment was run through
completely and correctly, the instrument will be locked and hence
ready for operation.
46 SITRANS LG250 - Operating Instructions PBD-51041388