mrmss
Lifetime Supporting Member
I feel a little embarassed asking this question since it's so simple...but if you dont ask questions...
I was playing around with the LIM instruction using LogixPro and wanted to prove that for Low Lim > High Lim; LIM is false when test value is between limits but true when test value is equal to or outside either limit.
Following table is taken from http://plcguide.mrplc.com/index.html
And the following statement is from The AB SLC 500 Instruction Set;
When I try this in LogixPro, my LIM is false when test is 2 or 6
I think it should be true for all values except 3,4 and 5.
Below, the CTU Accum value is 1 here and LIM is true as the Lamp is On. As expected.
Below, CTU Accum value is 2, this is EQUAL to the High Lim and I was expecting LIM to be true, LIM is actually false and Lamp goes Off. Not as expected.
When CTU Accum value is 3,4 or 5, as these values are between the limits - LIM should be false, lamp goes off. Works as Expected.
When CTU Accum value is 6, this is EQUAL to the Low Lim and I was expecting LIM to be true, LIM is actually false and Lamp goes Off. Not as expected.
Finally CTU Accum goes to 7, this is not within the limits, LIM should be true. Lamp goes on, works as expected.
Can anyone shed any light on this?
I was playing around with the LIM instruction using LogixPro and wanted to prove that for Low Lim > High Lim; LIM is false when test value is between limits but true when test value is equal to or outside either limit.
Following table is taken from http://plcguide.mrplc.com/index.html
And the following statement is from The AB SLC 500 Instruction Set;
"If the Low Limit has a value greater than the High Limit, the
instruction is false when the Test value is between the limits. If the
Test value is equal to either limit or outside the limits, the instruction
is true."
instruction is false when the Test value is between the limits. If the
Test value is equal to either limit or outside the limits, the instruction
is true."
When I try this in LogixPro, my LIM is false when test is 2 or 6
I think it should be true for all values except 3,4 and 5.Below, the CTU Accum value is 1 here and LIM is true as the Lamp is On. As expected.
Below, CTU Accum value is 2, this is EQUAL to the High Lim and I was expecting LIM to be true, LIM is actually false and Lamp goes Off. Not as expected.
When CTU Accum value is 3,4 or 5, as these values are between the limits - LIM should be false, lamp goes off. Works as Expected.
When CTU Accum value is 6, this is EQUAL to the Low Lim and I was expecting LIM to be true, LIM is actually false and Lamp goes Off. Not as expected.
Finally CTU Accum goes to 7, this is not within the limits, LIM should be true. Lamp goes on, works as expected.
Can anyone shed any light on this?
