Download a PLC program? Transport memories?

Mc_Topaz

Member
Join Date
Jul 2006
Location
Göteborg
Posts
4
Hello!

I have two questions:

1)
I'm looking for a link to a PLC program. A demo or a legal full program would not be wrong. But the program must handel Ladder, SFC or Function block diagram.

I used GX IEC Developer 6.0 in my High school, so I'm first searching for that. Also Dox10 maybe work to.

2)
I'm trying to program "Transport memory" which should be TRUE, while a transport of a material on a conveyor is moving in Step by step princip. I know this "Transpory memory" is used in car industies. But how do I program this memory?

I attached a Text file with a simple programming in Ladder. Can someone tell me if I'm correct or I'm just way off ;)
 
From a quick look, your not tracking anything, just starting the motors when an object is there and stopping once cleared.

I'll look again later (home time) if no-one else has helped out I'll give it a better look.

Just a quick one though, is motor1, motor2 etc, your outputs? If so you can't program the coils twice as the last one will take precedence, i.e if network for 1 to 2 turns on the outputs for 1 and 2, the next next network, for transport from 2 to 3 will turn 2 off again and the thing your transporting will not travel onto 2.
 
Normally for this type of tracking, the object would be detected by a PEC (Photo Electric Cell), not that a proximity cannot be used if you have good tolerance on side movement, but normally you'd be looking for the PEC feedback to be broken by the object. So the polarity for the logic would be Closed for No Object and Open for Object detected (opposite to your example).

The other thing to look out for is the outputs that I mentioned above. There looks to me to be a few interlocks not really needed.

I won't write up my version to achieve what you want as you won't learn, better to figure it out by yourself.
 
PeterW said:
From a quick look, your not tracking anything, just starting the motors when an object is there and stopping once cleared.

I'll look again later (home time) if no-one else has helped out I'll give it a better look.

Just a quick one though, is motor1, motor2 etc, your outputs? If so you can't program the coils twice as the last one will take precedence, i.e if network for 1 to 2 turns on the outputs for 1 and 2, the next next network, for transport from 2 to 3 will turn 2 off again and the thing your transporting will not travel onto 2.

Yes, Motor1 to 3 are outputs as well Se1 to 3 are inputs.

In your second post I didn't understand the first message.

I add some stuff in the .txt file, but I couln't see why this should not work. I put the new version of the .txt file in this post.
 
The bit you don't understand.

For your inputs Se1 to Se4, you have programmed the code to say, if the input is ON, then there is an object to move. This is not neccesarily wrong, but from my experience it would be the other way around, an object is there when the input is OFF.

A proximity switch is a sensing device, which detects an object close to it, anything from 1mm to 5mm is normal, although you can get some to sence a bit further.

On a conveying system, you would not normally use a proximity switch unless you can guarantee that the object will be within that sensing distance, that is the object fills the space between the side walls or the objects build back pressure which will force it against the switch.

The usual way for detecting an object on a conveyor is to use a PEC (photo electric cell), this is a device that emits a beam from one side of the conveyor and a reflector mirror on the other side of the conveyor reflects the beam back, so the PEC emits a beam and detects the relection back. When the object passes between the PEC and the reflector it breaks the circuit and at that point the PEC switches.

The advantage being your looking for an object the whole width of the conveyor.

This would normally be wired to give a signal when the PEC sees the reflection, therefore when the object obstructs the reflector the input goes OFF.

Both can be either way, but the most common methods are proximity gives a signal when an object is detected and the PEC gives a signal when an object is not detected.
 
PeterW said:
The bit you don't understand.

For your inputs Se1 to Se4, you have programmed the code to say, if the input is ON, then there is an object to move. This is not neccesarily wrong, but from my experience it would be the other way around, an object is there when the input is OFF.

A proximity switch is a sensing device, which detects an object close to it, anything from 1mm to 5mm is normal, although you can get some to sence a bit further.

On a conveying system, you would not normally use a proximity switch unless you can guarantee that the object will be within that sensing distance, that is the object fills the space between the side walls or the objects build back pressure which will force it against the switch.

The usual way for detecting an object on a conveyor is to use a PEC (photo electric cell), this is a device that emits a beam from one side of the conveyor and a reflector mirror on the other side of the conveyor reflects the beam back, so the PEC emits a beam and detects the relection back. When the object passes between the PEC and the reflector it breaks the circuit and at that point the PEC switches.

The advantage being your looking for an object the whole width of the conveyor.

This would normally be wired to give a signal when the PEC sees the reflection, therefore when the object obstructs the reflector the input goes OFF.

Both can be either way, but the most common methods are proximity gives a signal when an object is detected and the PEC gives a signal when an object is not detected.

That PEF stuff and to "see something before it's marked by an object", was new to me. I made my picture from my school's conveyor system which doesn't use PEF things. We use normaly sensors which is ZERO or OFF went it's marked by something else is ONE/ON (I changed that in my picture). I don't use pro stuff, I just want the thing to work.

But if you forget your way to do it, do my solution work?
 
In PLC's you can use the outputs as contacts as well, so motor 2 is a coil which turns on a motor contactor, in the program you can then use motor 2 as well.
---| |--

So you don't need the double code, not a problem though.

You may want Se1 Se2 M_1 M_1
---| |--| / |--| / |---(S)

Se2 n/c in series, so you dont start until the next sensor is clear.
 
PeterW said:
In PLC's you can use the outputs as contacts as well, so motor 2 is a coil which turns on a motor contactor, in the program you can then use motor 2 as well.
---| |--

So you don't need the double code, not a problem though.

You may want
Se1 Se2 M_1 M_1
---| |--| / |--| / |---(S)

Se2 n/c in series, so you dont start until the next sensor is clear.

Yeah, I know I can use a motor or output as an input. But I rader not if I can do it without.

But it should work if: While Motor2 is running, I'm not leting the part from Se1 go.

It's seem to me their is numbers of solution for this. I shall work on setting a Motor as a coil too. Wont hurt ;)
 

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