Automated Parking System Using OMRON PLC and HMI

[Lancie1]

Using reed switches with magnets wont cost me much either I guess ?

It is all relative to your budget. If you have the money, I have the time to make it work!

Reed switches have a poor reputation in industrial applications because they can stick open or closed. But they should be okay here. If one sticks you can jar it loose with a swift tap or by applying a strong magnet at different points.

 

[kannan_kathiresan]

Just scanned this post quickly.
The CP1L 24vdc supply is rated at .3 amps.

I am hoping the OP understands a separate supply will be required to run the 15 volt motors.

The inputs can be wired either sinking or sourcing, but all must be the same. This is determined by the COM connection on the terminal strip.

Hope this will help.

What does the the 0.3 Amps mean ? I don't understand

 

[kannan_kathiresan]

I don't think he does. He still thinks that the small 0.3 Amp power supply in his Omron PLC will be enough to power relays, motors and the PLC too. NOT! I think he needs to purchase a 24 volt external power supply, rated for 5 or 10 AMPS, not tenths of Amps. As Jordan pointed out earlier, one large 10 Amp supply with both 24 and 12 volt DC oututs would probably do the job of powering both the 15 volt motors and all the other 24 VDC stuff.

I have a SMPS that can supply 24VDC.
SMPS make: Meanwel - NES-100-24
Input: 100-120VAC . 2.5A .
200-240VAC. 1.5A.
Output: +24VDC and 4.5A

would this be enough ?

 

[kannan_kathiresan]

The 13360 Revolutions per Minute will tear the roof out of your lift before you can stop it. If you use this motor, you will have to limit your voltage to about 5 volts so that is does not run away and destroy your lift before you can stop it. 100 RPM max would be better!

Also the power rating is 2.85 Amps. You need a power supply for 2 motors at 2.85 Amps. I don't think 0.3 Amps is going to do the job!

That applies for my entrance gate and exit gate also right ? all four motors similar ? DC 24V would be the best right ? 100 RPM for all four motors? I don't understand the power rating part . Could you please explain ?

If I have a 12VDC motor only, I have to use a relay and voltage regulator and a heat sink right ?

 

[kannan_kathiresan]

It is all relative to your budget. If you have the money, I have the time to make it work!

Reed switches have a poor reputation in industrial applications because they can stick open or closed. But they should be okay here. If one sticks you can jar it loose with a swift tap or by applying a strong magnet at different points.

I have a budget of up to 300 MYR which is about 100USD. The university will sponsor me for this amount.

Good that you already warned me I will buy the NO type reed switch .

 

[kannan_kathiresan]

Yeah, ratings get odd for the glass switches. These are rated in Pull-in Sensitivity and Drop-out Sensitivity. This is measured in Ampere Turns which is a measure of magnetic strength. The lower the number, the more sensitive the sensor is. You may have to experiment a bit to see what woks best for you.

EDIT: Forgot to add, the ratings are okay to use for PLC inputs.

Awesome !!! Are there any similar technologies in place other than the reed switch and spring method ie ?

 

[OzRoo]

You could also put a reflector on the wall one side or below with a photo eye beam sensor looking for the reflector, though you need a tight beam or laser type to not shoot around a matchbox car.

 

[Lancie1]

Output: +24VDC and 4.5A. Would this be enough ?

It depends on your total load. Don't ask me because I don't know what you are going to connect. Add up the ampacity of each load and see if it is less than 4.5 Amps. For your DC motors, you are going to want them to run at a very slow speed. How do you reduce the speed of a DC motor? Reduce the voltage! It is usually very linear. If you reduce the voltage on a 15 volt motor to 7.5 volts, it will probably run at about 1/2 speed. So use that rule to determine how fast and at what voltage you want your motors to run. There will be some minimum voltage below which the motor will stop turning.

 

[Lancie1]

If I have a 12VDC motor only, I have to use a relay and voltage regulator and a heat sink right ?

Not exactly. If your 12 VDC motor runs 1000 RPM at 12 volts, but you only need it to run 250 RPM for your lifts (safer and more realistic), then if you cut the voltage down to 1000/250 or 1/4 of 12 = 3 volts, then all you need is a 3 volt supply and a relay and no regulator.

That assumes that your motor will turn at 3 volts. For the 13360 RPM Como Drill motor you listed, 4.5 volts is the minimum that it will turn. For that one, a 5 or 6 volt DC power supply would be ideal to keep the speed lower. (It still will be too fast for a lift, without a gear reducer).

 

[kannan_kathiresan]

Not exactly. If your 12 VDC motor runs 1000 RPM at 12 volts, but you only need it to run 250 RPM for your lifts (safer and more realistic), then if you cut the voltage down to 1000/250 or 1/4 of 12 = 3 volts, then all you need is a 3 volt supply and a relay and no regulator.

That assumes that your motor will turn at 3 volts. For the 13360 RPM Como Drill motor you listed, 4.5 volts is the minimum that it will turn. For that one, a 5 or 6 volt DC power supply would be ideal to keep the speed lower. (It still will be too fast for a lift, without a gear reducer).

Yeah, I understand the concept of minimum voltage = minimum speed. The problem is my PLC will supply a 24VDC to the motor via a relay. I need the feedback from the motor to see when its on and off to display it on HMI. The feedback part I can use one more relay. But, how do i initially step down the 24VDC from PLC .

 

[mendonsy]

Your motor current exceeds the output relay rating of the PLC so you will need at least two 24vdc relays to switch the low voltage to the motor, one for forward, the other for reverse. You could use an extra contact of the relays to a PLC input to indicate run on the HMI or just monitor the PLC outputs that control the relays.

 

[kannan_kathiresan]

Your motor current exceeds the output relay rating of the PLC so you will need at least two 24vdc relays to switch the low voltage to the motor, one for forward, the other for reverse. You could use an extra contact of the relays to a PLC input to indicate run on the HMI or just monitor the PLC outputs that control the relays.

Or I can find a relay module with a higher current rating ?
Or I can change the motor ?

So basically, the motor current should be less than the output relay rating ? Why is this so ?

 

[mendonsy]

The output relays are built into your CP1L. They cannot be changed.
The relay contacts must be a higher current rating than the motor to prevent damaging them particularly when they open and close. The starting current will be much higher than the running current.
You may be able to use a smaller motor, but even so I suggest using external relays to drive the motor. They are a LOT less expensive to replace than the whole PLC if you make a mistake.

 

[Lancie1]

The problem is my PLC will supply a 24VDC to the motor via a relay.

No, no, no. Your PLC cannot supply ANYTHING to a 4.5 Amp motor except a signal to switch a relay WHICH is what turns on the motor. Get the idea out of your head that your PLC will be passing its own 24 VDC supply (rated at 0.3 Amps and not enough power to run ANY motor that you have mentioned) on to a motor. It can not, and if you wire it that way you will burn out your PLC output.

Because you MUST use a relay (to switch voltage from an external power supply to your motor), then you can use any voltage to run a motor that is needed. Therfore select the power supply voltage to run the motor at a low rpm so that you can wind up cable on a drum at a slow rate for your lift. Forget the regulators and all that junk - only complications for no good reason.

What you need to do is draw some schematic wiring diagrams to clarify your design. Right now you don't have a clue about how it needs to be wired.

So basically, the motor current should be less than the output relay rating ? Why is this so ?

It is simply good common-sense design logic. If the motor relay (not a relay inside your PLC) does not have a current rating larger than the motor current, it will get hot, the contacts will burn or stick together, and very shortly it will no longer work.

 

[Lancie1]

I looked up the Omron Sysmac CP1L-M40DR-A. It has 16 relay outputs rated for Coil voltage of 120 to 240 VAC, but the current rating is only 2 amps per output. So the internal relays can be driven with the line supply, and the external motor relays will need to have AC coils for the same AC line voltage. Each motor that needs to reverse will need a relay with 2 Normally Open contacts.

I have attached a partial schematic wiring diagram for this arrangement, with only the outputs shown for the 2 lift motors.