What is the easiest way to program a keypad into a slc 500?

I need a little help in solving the logic to have a keyboard interface with the plc. I need the logic to enter a password and also be able to reset the password.

Tell us more about your application. Are you talking about an honest-to-goodness keyboard, like the one with the PS/2 plug that goes into your computer ? Or do you mean a PanelView operator interface terminal that has a Keypad type data entry object ? Or do you have a keypad with digital outputs (maybe encoded as BCD) that you want to be able to enter values into the SLC ?

And what sort of Password are you intending to change ? If you're talking about the SLC password, then you can stop right away; only RSLogix 500 software can change that password. If you mean a password for some kind of machine operation, then please explain the idea.

key board help

My key board is actually a keypad with 10 digits 0-9 and * , # keys It is a bcd input into the SLC 500. The password would be used in the program.
The program is a simple home security project. I would like to be able to change the password by using the key pad.

Aahhhhhh BCD

I love coded stuff! BCD needs 4 inputs for your system to work. Presuming that the key pad only outputs one BCD character at a time when you push a button, it should have only 4 wires coming out. One for each bit of the BCD word. So, 1746-IG16 is a good choice if your pad is outputting in the TTL/5vdc level arena. If not, pick another module of appropriate voltage rating for your pad. The programming is going to be the trick with this application so do some coding and come on back here if you get stuck! Good luck!

Lets say the keyboard is installed and will write BCD to the PLC. I am curious how you might use it to incorporate a numerical password into a program.

My imagination isnt that good but I have attempted to think of ways that would require you to input a number to "lock" the plc out but havent thought of but one and I am reluctant to ask if that would work. Even when an AB program is locked an HMI can read or write to it in most cases...correct? The password thing just requires you to have an exact copy of the plc program..correct?

Sitting here writing this I did think of something, a CMP could be used to turn on or off a bit..I think. The problem would be creating a way to "change" the numeric value from time to time.

I know I am rambling but this concept intrigued me.

great start

thanks, for getting me started. I enjoy the challenge of trying need programs. My one big question is am I over my head. This is for a lab project at PSU. (first year of programming a PLC) I understand what the reply I was given. But Im a little on how to start the ladder. the use of the input values can be used. But How do I get them into the processor. So far all we are using is simple switches it activate an input. Suggestions and Help please.

Post what code you have on this site. Someone here will correct any errors to get you on the correct track. Hopefully we wont do it all for you. Regards Alan

I maybe know how but...

Hi, I know your problem but the only thing is I can do it on whatever Siemens PLCS maybe if syntax en logic is similar or easy to translate I could help.

Well, James, let's begin with identifying the input data points that are associated with the keypad.

Follow the wires from the keypad to the Input module in the controller chassis, and identify which Slot number the module occupies (the CPU is Slot 0, and numbers increase 1,2,3.. to the right).

Input module data in an SLC-500 is represented as follows:

I:x.y where x is the Slot number and y is the Bit number.

Poke around on the keyboard a little bit and figure out which bits are turned on by each keypress. You might even want to write them out in a truth table.

You're going to need to learn about the Masked Move (MVM) instruction as well as the FRD (Convert BCD to Integer) instruction. Look them both up in the Instruction Set Help section of the RSLogix 500 programming software.

As with most programs, the procedure is more important than the code. Write down, step by step, what you thing the SLC-500 needs to do with those keypresses, and converting those steps to ladder logic will be a lot easier than just sitting down and starting to enter instructions.

I will try to put my code on tomorrow

You guys are a great help. Thanks for making it Burt and Ernie for me.
Let me take a crack at the program on thurs the 27th then I will Yell for help.

Thanks for making it Burt and Ernie for me.

Click to expand...

Having lived in London for a good few years, I know a lot of the ol' ****ney rhyming slang but I have never heard of a 'Burt and Ernie', I assume that it is something to do with those 2 characters in Sesame Street or was it the Muppets?

Anyway could someone enlighten me please.

Paul

Bert the Cop and Ernie the Taxi Driver are characters in Frank Capra's 1946 classic motion picture "It's a Wonderful Life". I have no idea what they mean to a Penn State student.

Mmm. Donna Reed.

PLucas said:

Having lived in London for a good few years, I know a lot of the ol' ****ney rhyming slang but I have never heard of a 'Burt and Ernie', I assume that it is something to do with those 2 characters in Sesame Street or was it the Muppets?

Anyway could someone enlighten me please.

Paul

Click to expand...

I think Bert and ernie are JoePa's children?

Don't get me wrong, I think JoePa is one of the great heroes of the game.

I just enjoy incrementing his "L" column.

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Bert and Ernie are part of the Sesame Street show shown in the US on PBS
http://pbskids.org/sesame/
I believe the reference was meant to state "how simple" you made the task.

I have 5 kids therefore it is mandatory I know these things along with facts about:
Pokemon
Yugi-Oh
Scooby Doo
Justice League/Batman (actually one of my childhood favorites)
Powerpuff girls ( I have one daughter)
The list goes on but these are the major ones at this time