# Tcl Transfer
tag2 value to tag1 if they differ by more that 0.1
#(similar to DATA
Transfer function).
# catch isolates
error,
# allows next
statement to execute rather than stopping entire
script
catch
{
if {[expr
abs([GETVAL sp1]-[GETVAL sp2])] >= 0.1} then {
SETVAL sp1=@sp2}
}
# abs is absolute
value - either .1 more or .1 less
# @ sign refers
to the contents of tag named sp2
# repeat for next
set of tags
catch
{
if {[expr
abs([GETVAL sp1]-[GETVAL sp2])] >= 0.1} then {
SETVAL sp3=@sp4}
}
The catch command “catches” errors, allowing the rest of the script to run. Without the catch, if there where in error in the last statement, for example tags sp3 did not exist, then the whole script would fail.