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Dear UNITRONICS users. Sometimes it happens that you need more digital inputs on the OPLC because of pushbuttons. A solution is an OPLC with a larger number of inputs or an extension needs to be added when is possible. That can be expensive. I developed a simple solution, which I named, the pushbuttons to current loop converter. In this case, you only need one analog input (4 – 20mA), to add up to 19 pushbuttons via two-wire shielded cable which can be up to 100m long. The converter is self powered ( powered from current loop ). The converter is reliable, since a very stabilized reference circuit is used. The error is maximum +/- 1 digit on 10bit AD I attach software for JAZZ with examples for easier understanding. It can be also used with others OPLC. The converter is only available in our company for now. For further info write on Email firstname.lastname@example.org. Best regards Robert Mramor s.p. Pushbutton to current loop - debouncing.U90
The machine I've built punches holes into long strips of sheet metal. The sheet metal is fed through the machine in 1/4" increments. The operator inputs the position of the holes into the PLC. For example, if the part needs a hole punched at 2", 3.5" and 6", the operator keys in the 8th, 14th, and 24th location (since each position is 1/4"). The PLC then keeps track of the number of increments the sheet metal has moved and activates the hole punch at the appropriate time. My problem is that I want to allow the operator to enter a large quantity of numbers, and the way I'm writing my ladder now would make that very messy. I am trying to figure out vectors or arrays for this, but I am new to visilogic and don't understand the best way to go about doing it. I assume this form of data entry is very common and there is probably a good way to go about doing it. Could anyone point me in the right direction? The way I am doing it now is I have an "Equal To" function block, and I compare the current position of the sheet metal to the entered value. If that's true, the hole gets punched. For example, if the metal is at position 10 (2.5") and the user had entered position 10, the hole gets punched. The problem with this is I have to write a separate function block for each user entered position. I apologize if this doesn't make sense. I have only taken a couple classes in PLC programming and we did not cover this.