Quite often hold in logic is referred to as hold in logic. The disadvantage is that debugging can become more difficult because the Set (Latch) and Reset (Unlatch) symbols may be scattered throughout the program. Advantages include flexibility in programming because the Set (Latch) and Reset (Unlatch) symbols do not need to be in the same rung. These instructions simulate the function of an electromechanical latching relay.
In an Allen Bradley PLC they are called Latch and Unlatch instructions. When we use the term latching in a PLC it refers to changing the state of an output to TRUE, holding the state of that output TRUE until certain conditions occur, then returning the state of the output back to FASLE. Latching is one of the most important pieces of ladder logic programming that you’ll ever use. Let’s take a look at some very simple, but extremely important ladder logic programming examples… Latching in a PLC
So by creating ladder logic programming examples we can speed up or overall programming time.Ĭonstructing a program is then a simple matter of grabbing the appropriate ladder logic programming examples and connecting them in an orderly fashion. Experience tells us that once a piece of ladder logic is created that accomplished a specific task it can be re-used in other areas of the program and in other applications as well.