Ladder programs for PLCs

Unless you drive like my girlfriend!

My plc experience has been limited to the allen bradley world. PLC2, SLC150, PLC500. We are using something called RSLogix 5000 now. I'm not sure I like it that much but it has neat things like a SQL interface stuck in a slot so it isn't all bad. I think that is called an Xcoupler.

Looking for simple inputs and outputs is a bitch though. I'm used to being able to see slots in a rack. No training so maybe I'm missing something. Just see a bunch of tags. I tend to look at prints and open the cabinets and trays where the flex IO is located to see what is happening when troubleshooting.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

(snip)

A bell just went "bing!" in my head -- do you need to find a smart kid who can make this happen under direction? I.e., if you can't _find_ the person to do the job, can you _make_ one?

There is a program called logixpro

You need to decide what PLC's to go with because the learning and software will probably be a larger investment than the hardware that you can probably find on eBay.

Years ago Mitsubishi electric was clearing out some of their older controls and I bought a few of them on eBay, they came with programming software. What you have to decide includes do you want 24V DC or 120V AC power to PLC, input voltage, output voltage. Do you have any PLC programming software available now? Relay outputs will work with 24V DC or 120V AC but mechanical relays have less life than solid state transistors (24VDC) or SCR/Triacs(120VAC).

I kind of like 24VDC for inputs and 120VAC for outputs, this gives you high speed for inputs and more output power to drive valves, etc. For example, if you have an output card current rating of 2A, that would be up to 48 Watts DC or up to 240 Watts AC for the same current, can help if you're driving multiple valves.

If you decide on a PLC I can help you through getting the program to do whatever you want it to. One of the cheapest to get working PLC's is the Automation Direct PLC, but I'm not sure on their quality, not sure if you would be better off with Automation Direct or something else.

The modular racks are nice because you can get cards for whatever you want, you can have some AC and some DC input and output cards as you need. If you use a fixed I/O PLC you could use relays to convert between the AC and DC in's and out's.

RogerN

Hows the weather in Lapeer?

Gunner, formally from the UP and Grayling

One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch

of tags. I

located to see

I much preferred tags. Having to use a physical address everywhere in the programming kept me from adopting plc's for quite a while. The mapping of tag to physical address happens at tag definition usually, although not always. I had occasion to use a fair bit of repetive programming, lots of similar pumps, etc. Tags made it easy. Just copy, paste, change the physical address. I did a fair bit of control stuff, but it wasn't my main job. Now that I'm retired, I don't expect I'll be doing that again.

Pete

Oh, I never used physical addresses except back when I was using a hand held programmer for a SLC 100 or 150 and some other ancient thing.

As soon as I was using PC based programming software, I used symbolic addressing so I:1/2 was refered to as UP_PB (up push button). Much easier to program that way. To a degree with good symbols the code tended to be self documenting.

I've run into machines where the original ladder files with all the nice comments and such couldn't be found. I end up plugging in, grabbing a current processor image and then determine what various buttons, switches and coils do and start using symbols to name them in the ladder so I can form a mental picture of what is going on.

Wes

Actually quite nice right now. Where in the U.P.? I co-own 40 acres with my brother in Seney. A Seney neighbor lives in Gaylord.

Ah yes..the Seney Stretch..the worst place I ever picked to hitchhike in Febuary.

I grew up in Hancock and Calumet, wound up in Grayling at the age of 14, graduated from there.

Most of my family are Yoopers, many of who flocked to Detroit for the war, but many stayed in the Copper Country.

Gunner One could not be a successful Leftwinger without realizing that, in contrast to the popular conception supported by newspapers and mothers of Leftwingers, a goodly number of Leftwingers are not only narrow-minded and dull, but also just stupid. Gunner Asch

Give an example of what you want to make a machine do and I and/or others can provide logic. Take it step by step, don't describe the whole operation but just the first step. We can provide sample code to perform the step and you can understand how each step works, and apply it to your machines however you need to.

For example, it is common to have a run mode for a machine that is enabled when you press a "Start" pushbutton and latched in until you press the "STOP" button or an E-stop, safety switch, or any sort of interlock is broke. For this you normally wire through contacts so that power is made to the input so the input is ON when it is in the safe condition, that way, if a wire is broke in the safety circuit, the thing stops running.

START STOP RUN |----| |----|----| |-----( )--| | | | RUN | |----| |----|

This says if the start button is pressed while the stop input is on (safe to run) then the run memory comes on. Once the run memory comes on it branches the start button so the start button doesn't have to be held in.

Then you might have something like this:

RUN AUTO_SS AUTO_MODE |----| |----|----| |---------( )--| | | AUTO_SS MANUAL_MODE |----|\|---------( )--|

OK, then you might have a rung telling when everything is in home position, perhaps the initial position needed for all system go, ready to start. If it is in auto mode and homed, then it can run the automatic cycle. If it is manual position it can be homed with a home button or operated manually as needed.

The cycle normally involves a step and detecting when that step is done, often a dwell timer before the next step starts. Eventually this gets back to the position to start the next cycle and it is repeated. You can have a condition for a "Stop at the end of the cycle" to stop the machine without crashing the current cycle. At the end of the automatic cycle, it checks "Stop at end of cycle" and stops or continues operation.

I would recommend just starting to update a machine and ask questions when they arise, it seems there are plenty of people on here knowledgeable and willing to help. Once you get walked through one machine you can probably get through 95% of the next machine before you run into something you have a question on.

If you know the machine and you know the program, you will be able to modify it for better performance or upgrade the automation, such as interface it to work with an automatic feeder or robots and such.

RogerN

:Xns9D97494D258F8lloydspmindspringcom@216.168.3.70...

co.com/controllers.htm

I down loaded their help demo tuturial, and got the non working software. Wow, this was too cool. Does any other vendor have this simple of a ladder logic coding software, I never could figure out how to get the automation direct demo to work.

The development kit, is a $300 with shipping, for the one with RTC, a little pricy. My first project is to take the manual surface grinder, and install power feeds, and use a PLC to control the surface feed, and cross step. The verticle is a little trickyer as you can't trust that a tenth down, won't jump 2 thou, at least on this 6x12 HF.