Created Date: August 16,2012

Created by: Tubecut

Although you mentioned you do not want to use a touch screen verses a keypad, I would take a look at the Cmore Micro series of touch screens. They are cost effect, has free software and several configurations including a color option. Also, single vendor support if needed.

If later you decide you need additional functionality that requires keypad changes, only a program change(s) are required.

I have used the Click/Cmore Micro configuration as well as using the Click serial port for I/O and

the Touch Screen seemed to be a lot less trouble.

Just a couple of thought.

Created Date: August 17,2012

Created by: BrianG

1. This application is for a children's museum. I have concerns that a C-more touch screen simply will not stand up to the repeated pressing of the numbers.

2. The panels are just too expensive ($324) for this application. I can get a keypad for less that $70.

I must not understand how the keypad sends the the "signal " back to the PLC. I thought it was basically like 16 push buttons with a pin attachment for ribbon cable.

Created Date: August 17,2012

Created by: Adisharr

1. This application is for a children's museum. I have concerns that a C-more touch screen simply will not stand up to the repeated pressing of the numbers.

2. The panels are just too expensive ($324) for this application. I can get a keypad for less that $70.

I must not understand how the keypad sends the the "signal " back to the PLC. I thought it was basically like 16 push buttons with a pin attachment for ribbon cable.

Most keypads are arranged in a matrix format - assumming a 4 x 4 keypad, you would have 1 wire for each row and 1 for each column (picture each key being at the center of where the wires cross. They are read by strobing one row at a time (or column) and reading each of the columns (or rows) to see what keys are currently pressed.

You might be able to get one with an integrated decoder to get you discreet signals for each key. If so and it's in your budget, you might just want to go that way as it will handle the key debounce and pulsing from the strobing routine.

Created Date: August 17,2012

Created by: BrianG

Okay, so a specific button is a combination of a column and a row. Can't I just make my LD something like this:

--| |-----| |------( )--

X1....... X2....... Y1

X1 being the column and X2 the row.

If the keypad has an encoder I presume it's function is to tell me exactly which key was pressed. That means I will no longer connect directly to the input module of the CLICK, correct?

Created Date: August 17,2012

Created by: Adisharr

Okay, so a specific button is a combination of a column and a row. Can't I just make my LD something like this:

--| |-----| |------( )--

X1....... X2....... Y1

X1 being the column and X2 the row.

If the keypad has an encoder I presume it's function is to tell me exactly which key was pressed. That means I will no longer connect directly to the input module of the CLICK, correct?

That won't work because you have to apply a voltage to each row and then see if it appears in each column on the inputs.

Example:

1 2 3 4 C

R

1 X X X X

2 X O X X

3 X X X X

4 X X X X

The user presses key at R2C2.

If you 're sequentially applying 24V at rows 1-4, when you 're at 2, the 24V will show up on column 2. It will be a pulse if the user holds down the key.

It will look like this..

_ _

___ ___ __ etc (square wave)

With the immediate I/O refresh functions on the Click it should work fairly well since you don't have to worry about the normal I/O refresh to make sure the I/O is physically updated.

Created Date: August 17,2012

Created by: Adisharr

I think I will just make myself a panel with 16 small (12mm square) pushbuttons. I'll just look for a supplier of numbered buttons that the kids can't take apart.

Thanks for your input.:)

Sure thing - that will certainly work. The main advantage of multiplexing is the I/O savings. 16 for discreet buttons and 8 for a 4x4 matrix. The savings increase as you 're button count grows.

8 x 8 matrix (64 keys) = 16 I/O vs. 64 I/O

If you decide you want to try the matrix, I could write a small routine to handle it. You could test it with just wires.

Created Date: August 18,2012

Created by: Tubecut

I see from your post why the concerns with using the touch screen in that environment.

I am attaching a app type note I posted some time ago. It may be useful for what you are

attempting to accomplish.

If you get interested, then locate the data sheets and make sure you understand the chips

referenced. Especially the two caps used to set the scan and debounce timing for the scan chip.

The ULN device allows the the circuit to interface with the 24 VDC normally used with the PLC.

BTW, I think the Click has 5-12 volt input modules that could simplify using something like

the suggested circuit.