My first PLC project finished!

jstolaruk · Oct 13, 2017

Mispeld said:
Something to consider is additional emergency stop push buttons along the conveyor. I see one on the main panel, but consider the following scenario: someone lifts a door at one of the center sections, and does so in a way that the proximity switch loses detection. The person exceeds the allowable time delay, and it triggers the start sensors to index a door into that section. Now the person drops the door, but is it too late to stop a "train wreck?"

This is where e-stop button(s) along the conveyor frame can allow for a rapid shutdown. Otherwise the person must run over to the main panel to e-stop.

The challenge is locating the e-stops such that they are not accidentally bumped, yet still easily accessible in an emergency. I would be looking for places under the rollers, near the conveyor legs, and recessed to avoid inadvertent hits.

An E-stop pull cord running the length of the conveyor is the correct switch on something like this provided the Risk Assessment calls it out as a hazardous condition.

janner_10 · Oct 13, 2017

backendcode said:
Thank you for the response janner_10,

Actually, I put 3 seconds delay at every prox to avoid the situation where somebody comes and lifts up a part(door) for a second, It stops because of debouncing time.

Thanks again,

I was joking with you!

Mispeld · Oct 13, 2017

jstolaruk said:
An E-stop pull cord running the length of the conveyor is the correct switch on something like this provided the Risk Assessment calls it out as a hazardous condition.

Yes, I was coming at it from a NFPA-79 perspective where the e-stop is intended to protect equipment and material.

Certainly, if a machine safety risk assessment under a standard such as ISO 13849 identified hazard(s) to personnel, safety devices such as a pull-cord switch may be called for.

I will not speculate about potential safety risks based on a short video.

swedeleaner · Oct 13, 2017

Confusing

Why isn’t a HMI-panel used? In Sweden you probably end paying more for Rhode öight pushbuttons + the additional programming they require.

backendcode · Oct 13, 2017

Mispeld said:
Something to consider is additional emergency stop push buttons along the conveyor. I see one on the main panel, but consider the following scenario: someone lifts a door at one of the center sections, and does so in a way that the proximity switch loses detection. The person exceeds the allowable time delay, and it triggers the start sensors to index a door into that section. Now the person drops the door, but is it too late to stop a "train wreck?"

This is where e-stop button(s) along the conveyor frame can allow for a rapid shutdown. Otherwise the person must run over to the main panel to e-stop.

The challenge is locating the e-stops such that they are not accidentally bumped, yet still easily accessible in an emergency. I would be looking for places under the rollers, near the conveyor legs, and recessed to avoid inadvertent hits.

I suggested putting the Estop at the end of the conveyor, where someone will offload the product (Doors).

Also, I stop the conveyors in unmatched condition

Example, when part present on conveyor 1 and no part present on conveyor 2. My motor turns ON to move the part from conveyor 1 to 2 but lets say the part is in between the conveyor 1 and 2 and this conveyor will stop when the part will hit sensor on conveyor 2 but someone picks up the part while it travellin from conveyor 1 to 2. In that situation, my motor will never stop because the part will never reach at conveyor 2 as it has been picked. so every time when part leave from 1 conveyor, I start the timer and let's say average time to reach part from one conveyor to another conveyor is 5 second but if a part doesn't reach in 15 seconds means either part stuck or picked up. the conveyor will stop by a DN bit of that timer which will DN after 15 seconds.

Thanks,

backendcode · Oct 13, 2017

LoganB said:
I've looked through your code a few times to give advice, so I remembered seeing the delay timer

Another trick a lot of us use is to place a timer in your fault logic routine on a rung with NOTHING but an XIO for that same timer's DN bit to the left of it. This setup creates a timer loop so that it will continue to count up, reset, and count up again whenever the machine is in run mode. Set the timer's PRE to 1000ms (1 second).

Then, in your fault logic where you are turning on the fault light on your control panel, please a LEQ (compare) to the left of the OTE that activates the light and tell it to compare the TON's .ACC value to 500. This means while your timer is running and your machine is in a fault state, the OTE to activate the light will be ON for half a second, then OFF for half a second. A blinking light is much more likely to catch someone's attention than a solid one.

You can adjust the TON's PRE and the compare value to change the rate that the light blinks. A PRE of 2000 (2 seconds) and your LEQ using 1000 will make a light that is on for 1 second, and off for 1 second.

hahahaha, i realized that. I am like LoganB must remember my PLC code now because you have looked so many times

Yeah, I can create a loop to blink the light for attention! Nice suggestion

Thanks,

backendcode · Oct 13, 2017

swedeleaner said:
Why isn’t a HMI-panel used? In Sweden you probably end paying more for Rhode öight pushbuttons + the additional programming they require.

My company is so cheap lol and they outsourced panel building and we programmed in house. Moreover, I don't know how to program HMI but I am going to use/learn HMI programming very soon at my next job

Firejo · Oct 13, 2017

Nice job. Satisfying, isn’t it? The only thing I don’t like about finishing a job building it is most of the fun.

swedeleaner · Oct 13, 2017

Ohh, so there is an HMI somewhere near by?

Good! As a programmer it’s always a challenge to create user friendly operator terminals.
Many have tried, few have suceeded.

I wish good luck to you young padawan!

kwade · Oct 13, 2017

Nice work.
Thanks for posting the results.
Also, thanks for uploading a high res video!

rQx · Oct 14, 2017

swedeleaner said:
Why isn’t a HMI-panel used? In Sweden you probably end paying more for Rhode öight pushbuttons + the additional programming they require.

Say what? With this few pushbuttons and lights an HMI would be more expensive in my mind

With that said if you add an HMI you could get more overview more settings, and alarm handling. It's always a choice of money/time/functions

My first PLC project finished!

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