HELP w/ CLICK Controlling a Feeder Bowl

There is a problem w/ the logic to control a Feeder Bowl to stop when the Lin. Trck is fully populated. There are (light) sensors at each end of the Lin. Trck. The machine has two modes of operation, and the population of the Trck is active in both modes. When the machine is powered up, NOTHING happens until an "ACTIVATE" button is pressed. The machine cycles through a HOMEing Seq, part of which is to determine the population of the Lin. Trck. IF either sensor is NOT made, then the Feeder Bowl will be powered & stay powered until BOTH sensors are TRUE. However, the sensor at the end of the Lin. Trck constantly "sees" a part, so once it is TRUE, it remains TRUE for the complete population process. However, that is NOT the case w/ the sensor at the Bowl end of the Lin. Trck. As a part passes through the beam, the sensor is TRUE, and then turns FALSE. So, to eliminate false reports, I've attempted to build in a "delay" reading of that sensor, using a toggle coding. Sometimes it works correctly, sometimes not. Therefore, I know that the coding is NOT stable.

I have tried to change the contact status of the X005 contact which controls the "toggle" logic. At first I used normal open & normal closed contacts, but that didn't seem to work. Then I switched them to Rising edge / Falling edge contacts, and that too didn't work reliably. And, finally, I switched them to Immediate contacts, with the same improper results.

All the Inputs, Outputs, & Marker contacts are properly defined, so anyone studying this Ladder segment should be able to follow, BUT in case there is doubt, I can certainly fill in the blanks.

Please note: The code segment is just that. It is NOT the entire operational Ladder for the machine. In order to reduce clutter, and make it more succinct, I culled out the pertinent sections only.

As I see it right now X005 must remain on steadily for 2 seconds minimum. At some point after that, while X005 is still on, X101 must make. That combination will turn off C172.

bernie_carlton said:

As I see it right now X005 must remain on steadily for 2 seconds minimum. At some point after that, while X005 is still on, X101 must make. That combination will turn off C172.

Click to expand...

No, that's not how it works. X101 is at the far end of the Lin. Trck., so once a part gets to that end, it makes the X101 TRUE, and it stays TRUE until the PICK & PLACE mechanics removes the part for processing. The X005 sensor is at the input end of the Lin. Trck, so while the Lin. Track is NOT fully populated, parts are passing by in short order. But, the sensor (a BANNER Q12 style Retro-reflective) switches from FALSE to TRUE to FALSE, as the part passes under the beam. That's why I used the software toggle w/ the C173 & C174 markers to start & reset the Timer which interrupts the row which tests for the TRUE X005 condition. IF that sensing delay (T203) wasn't in the logic circuit, the X005 sensor would cause the Feeder Bowl to prematurely stop delivering parts.
The problem is that once the Lin Trck IS fully populated, the Feeder Bowl does NOT always become de-energized. I said, "NOT always", because on some random occasions, when I've started the machine cycle from the same original conditions, the Feeder Bowl will energize, deliver parts to the Lin. Trck, and then properly de-energize. But, this happens ONLY occasionally, NOT consistently, so that's is why I know I've screwed up the logic somewhere, but I haven't been able to isolate my error.

I was just noting what your code is doing, not that it is doing what you want.

My description implied that X101 would have to turn on after the 2 second time. But it can turn on any time. It just must be on after the 2 second solid on time of X5 to turn off the feed.

The timing begins once the input logic using C170, C199 and Y003 is true. if you turn on you will still require the two second ON time of X5 from that point.

Actually, if X5 is already ON when the system starts then there won't be an ON edge for that input.

bernie_carlton said:

I was just noting what your code is doing, not that it is doing what you want.

My description implied that X101 would have to turn on after the 2 second time. But it can turn on any time. It just must be on after the 2 second solid on time of X5 to turn off the feed.

The timing begins once the input logic using C170, C199 and Y003 is true. if you turn on you will still require the two second ON time of X5 from that point.

Actually, if X5 is already ON when the system starts then there won't be an ON edge for that input.

Click to expand...

I don't have a problem w/ either the C170 or C199 markers. They properly handle the entrance into this block of code depending on the state of the machine, whether it is in its HOMEing Seq mode, or the OPERATE READY mode. ANDing the Y003 contact of the LIN. TRCK output only ensures that this block of code will NOT execute UNLESS the Lin. Trck IS energized, which is done elsewhere (& without problems).

Since X101 is at the far end of the Lin. Trck, it sees a part as stationary once the part appears at that point. Therefore, it becomes TRUE for the entire Lin. Trck population process. So, that sensor is NOT the problem.

I am attempting to use the toggle in concert w/ T203 to DELAY the sensing of the part passing under the beam of the X005 sensor only. I have set T203 @ 1500 ms, since that seems to be a sufficient amount of delay to prevent false triggering of the T204 Timer, which ultimately controls the HSG BOWL OFF contact.

The problem that I'm having is that there is a logical (or scan timing) error with the rows that SET & RESET the two markers C173 & C174. That is where the crux of the problem lies, I believe. As I've previously stated, using the N.C. contact & the N.C. for X005 in those two rows didn't work correctly to SET or RESET C173 & C174. So, then I tried to use the IMMEDIATE form of the contact X005 (N.O. & N.C.), and that failed also. Finally, I tried the Rising Edge & Falling Edge form of the X005 contact, as it appears in the Ladder that I forwarded to you. And, that too, does not work reliably. So, I KNOW that there is a logical coding error, but I have NOT isolated it yet, and that's why I've called for some professional assistance.

Would it be valid to say that if X101 is ON and X5 has been on steady for 2 seconds then stop? Is that what you want? I'm trying to get the simplest description of what you want.

bernie_carlton said:

Would it be valid to say that if X101 is ON and X5 has been on steady for 2 seconds then stop? Is that what you want? I'm trying to get the simplest description of what you want.

Click to expand...

YES!..... BUT ONLY IF X005 stays on for a period of time LONGER than what it takes for a part to pass under the beam. Bernie, understand that the sensor is a simple BANNER Q12 type (retroreflective) with a 15mm Sensing Distance. Therefore, I do NOT have the ability with this sensor to program it for a delay-to-sense, as is common with typical KEYENCE, etal. amplified light sensor products. That is why I have to have some sort of software accommodation for the part passing under the beam, so that it doesn't trip X005 unnecessarily. There are other areas of this machine which utilize KEYENCE fibre sensors, and I have programmed them with a delay-to-sense, and that has worked out fine. But for the Lin. Trck, it was not convenient (or $$$ wise) to do it.

YES!..... BUT ONLY IF X005 stays on for a period of time LONGER than what it takes for a part to pass under the beam

Click to expand...

That's what the combination of your two timers, T203 and T204, do. T204 wont time out unless X005 has stayed on at least as long as their combined presets.

I am attaching a much simplified version of your program. Set the preset of T204 (now at 2000 ms) for the continous ON time of X005 that you want to trigger the stop.

In this simplified program the logic to run the output is ((NOT X101) OR (NOT T204))
T204 is DIRECTLY triggered by X005. If it turns OFF the timing starts over.

Good job, Bernie. I was coming back to say there was a conflict between the old T202 (2 seconds delay after X005 sees part before Bowl Power) and the combination of T203 and T204 (keeps Bowl Power ON for 2 second delay after X005 sees part).

That was a good illustration of how using a lot of Sets and Resets gets so involved that the logic cannot be easily and quickly understood.

I love how you simplified it so that even a country boy like me can now understand how it works. :site:

Lancie - you made me look again.

In my simplified program remove the contact of C172 before the X005 contact in line with T204. With it as it is it will automaticcaly retrigger and turn back on.

Fixed file is attached

Good deal, Bernie. I bet it works better than the original, to say the least.

bernie_carlton said:

That's what the combination of your two timers, T203 and T204, do. T204 wont time out unless X005 has stayed on at least as long as their combined presets.

I am attaching a much simplified version of your program. Set the preset of T204 (now at 2000 ms) for the continous ON time of X005 that you want to trigger the stop.

In this simplified program the logic to run the output is ((NOT X101) OR (NOT T204))
T204 is DIRECTLY triggered by X005. If it turns OFF the timing starts over.

Click to expand...

THANK YOU!!!!! It's now 7:30 (E.D.T.) here. I will move this code into the program & test it.

A little background.... This was my FIRST attempt at LADDER. After building this machine, and getting it to run using a microcontroller, we knew that we would switch control to the CLICK which we purchased to learn LADDER. By last October, I was still "groping in the dark" despite the two textbooks I purchased on LADDER. They were either too general or TOO specific (Think SLICK!!), and I was getting confused. In an effort to move the project forward, I came upon a local fellow who gave me some very valuable instruction, and from there I took over completely. I DO have considerable programming experience (about 45 yrs), so the logic portion was fundamental. It was the effecting that was the roadblock. Overall the machine works, and it works very well. I'm SURE however that IF I subjected my total program code to a panel for review, it would be criticized because it is too bulky for what it is doing. I suppose it could be rewritten more efficiently. Sort of reminds me of the challenges I faced many decades ago in "tightening up" Assembler code as much as possible because EVERY byte of RAM was sacred back then.

Lancie1 said:

Good job, Bernie. I was coming back to say there was a conflict between the old T202 (2 seconds delay after X005 sees part before Bowl Power) and the combination of T203 and T204 (keeps Bowl Power ON for 2 second delay after X005 sees part).

That was a good illustration of how using a lot of Sets and Resets gets so involved that the logic cannot be easily and quickly understood.

I love how you simplified it so that even a country boy like me can now understand how it works. :site:

Click to expand...

Lance1: Here's some more of the overall operational logic. The Lin. Trck comes on as a separate rung control once the ACTIVATE P/B is pressed. The Feeder Bowl is delayed a bit BEFORE it can be energized to allow time for ANY remaining parts that are on the Lin Trck to advance to the end. This opens up the area underneath the X005 sensor BEFORE any condition-testing is done. Likewise, when the X101 AND X005 sensors ARE made (TRUE), there is a delay in shutting down power to the bowl (but NEVER to the Lin. Trck) to allow the last few parts to exit the Bowl tongue and transfer to the end of the Lin. Trck. The X005 sensor is NOT at the very end of the Lin Trck, but is recessed apprx. 1" to accommodate this movement hysteresis in the parts.
Finally, there are two more Timers, T205 & T206, which are there to keep track of the Bowl power when the Bowl is empty BUT there are still parts to be processed on the Lin. Trck. They have two different timing settings because one is used ONLY during the HOMEing SEQ. mode & one is used during the OPERATE READY mode.
I hope this explains a bit more of the operation. It's the obvious adage...... A picture is worth a thousand words, and MY corolly is, "the REAL thing is worth a thousand pictures!" IF y'all were here, the lights would shine in your heads in milliseconds...... I'm SURE of that!

bernie_carlton said:

Lancie - you made me look again.

In my simplified program remove the contact of C172 before the X005 contact in line with T204. With it as it is it will automaticcaly retrigger and turn back on.

Fixed file is attached

Click to expand...

THANK YOU BERNIE!!! I expanded both versions of your LADDER to see exactly what you're referencing.
I'm NOT trying to make this any more difficult than it has to be, but I read your description AND I looked at the rungs. And, I think that you & LANCIE1 have misinterpreted my goal. Here's why....
When the machine is initially powered on, the ONLY thing that happens is that a "Soft-Start" valve pair are energized. After a brief delay, the MAIN AIR Valve is opened, so the entire machine is powered w/ air. Since some of the actuators are connected w/ 3/2 valves, they automatically move to their "HOME" positions. Then, NOTHING else happens, UNTIL the P/B on the control panel marked ACTIVATE is pressed (momentary). At this press, the machine goes through a HOMEing SEQ process of 7 steps, two of which involve bowl feeding actions. The HSG FEED is one of these, and this is the one that has given me trouble all along. It is ironic in that the other bowl feed process involves a "blow-off" feature, yet I got this done correctly, with no malfunctions.
Now, the steps involved in the HSG FEED step are the following:
(Note- the Lin. Trck has been turned on by an independent rung, once the ACTIVATE P/B is pressed.)
1) After a (2 sec.) delay of the Lin. Trck being ON to give time for any remaining parts under the X005 sensor to move further down the Trck, the HSG BOWL is energized.
2) The idea at this point was that there should be a "toggle" logic, so that parts passing UNDER the X005 beam would NOT pulse the Bowl On & Off unnecessarily. In other words, it was meant as a "keep alive" logic. Therefore, the Timer, T203, HSG TRVL Snsr Dly, was inserted. The action intended was such that IF a part REMAINED under the beam of X005 AFTER the T203 timer elapsed, then it would be recognition that the Lin. Trck WAS INDEED fully populated.
3) At this point, the T204 Timer would be energized to let the few remaining parts that are in the "limbo" area between the end of the HSG Bowl tongue AND the entrance to the Lin. Trck to move onto the Lin. Trck. The controller for the HSG Bowl is a typical thyristor output circuit. And, as such, when the signal to turn on the Bowl is present, one NEVER knows at what part of the A/C power sine wave, the thyristor will fire. Therefore, the Bowl MAY start w/ a "bang". The controller has NO built-in "SLO-START" circuit.

That's the reasoning behind the ladder segment that I originally sent y'all, and WHY the intended complexity. I hope this more fully explains the intended action of this segment of the machine operation.

Bernie, I'm looking at the 2nd version more closely now. I've printed it out (onto paper) so I can study it. On the first row of the rung #4, you show a NOT T204 OR a NOT X101 to turn on the C172 marker. But, in practice, I'm NOT sure this will work. Here's the scenario..... it's the end of the day, and the machine is shut down for the evening, BUT there are SOME parts on the Lin. Trck. By virtue of the physical action of the Trck, there SHOULD ALWAYS BE a part at the far end of the Trck. X101 IS the sensor (BANNER Q12 style) which detects the presence/absence of a part at that position. However, IF the Bowl is getting low on parts, then there MAY BE an empty area along the Trck, closer to the Bowl. And, coupled with that is the fact that as the Bowl inventory is depleted, the parts DO NOT spiral up the bowl at the same rate,adding MORE time to the replenishment of parts to the Lin. Trck. And, one other item that I may not have mentioned..... the X005 sensor @ the near (Bowl) end of the Lin. Trck is NOT exactly @ the end of it, but is apprx. 1" in from that end of the Trck. I explained in an entry to LANCIE1 why this is positioned at this point.