Linear Actuators and PLCs

Hello,
I'm fairly new to PLCs and only know the very basics of how it works as well as some programming. My goal right now is to extend and retract a linear actuator using an omron CS1G. The linear actuator is rated for 12v and 3A max. My question is is it safe for the plc to do this? I know in order to extend and retract you need to reverse the polarity of the power supply. I could always use a DPDT switch however I would like to control most of it through the PLC for future projects.
Thank You

It is not common to use a PLC output to directly control that much current. Almost all outputs from a PLC that can handle it would be relay contacts. Relay contacts have a finite life expectancy, so if there are relays, it is better to have them separate from the PLC so that maintenance is simplified. AN overload condition of the motor could present additional problems better handled safely away from the PLC outputs.

In most cases with a linear actuator, you would use a positioner or a drive to control it. Some basic applications can be done with separate relays or contactors to handle the motor current. The PLC can manage the drive or relay signals and monitor the position.

You will have to read the manual for the linear actuator to know for sure how to run it.

You will likely run some relays from the PLC to control the actuator if you are switching power.

Hello thanks for the reply. Are you saying i would need some sort of external device or a relay ? If that is the case could you reccomend anything in particular ?

Linear Actuator....

...not enough information given.

What are the specifics of the linear actuator, and intended application.

Stroke Length?
Speed Required?
Frequency of reversal?
Motor Type, Servo, AC Induction, D.C.?
Motor HP?
Motor Voltage?
Motor FLA?
Positioning accuracy required for application?
]We look at all of the technical requirements first....

...then look at budgetary considerations second.

Agreed, we need more information.

If it is a simple discrete actuator whereby you apply power to get it to move one direction, and reverse polarity for the other; I like these relays:

Phoenix Contact PLC-RSC Series 24V dc DIN Rail Interface Relay Module, DPDT, Screw


RS Stock No. 434-1327 Mfr. Part No. 2967060 Brand Phoenix Contact.

The wiring is very simple. I have a system here, not PLC controlled, that I can show you.

My experience with linear actuators however is that most have a controller. The PLC sends command signals, either via simple digital IO, or using a FieldBus such as ModBus or Ethernet/IP. This allows for not just move positive or negative direction, but control of accel/decel, velocity, and feedback of status, alarms, position, force, etc

Please post the exact model numbers of all hardware you have.

You could use PLC outputs directly, but it isn't good practice even if they are rated for that current or more. Switching that much current will cause some arcing, which erodes contacts, so eventually you would need to replace the output card or PLC. It is better to use an external relay to switch the power and use the PLC to operate the relay coil.

Even better than relays would be using a reversing contactor. They have a mechanical interlock that prevents trying to move in both directions at the same time in cases of a programming error or relay failure.

https://www.c3controls.com/configur...508335848]=reversing#miniature-contactor-type

Another consideration should be end-of-stroke/mechanical restriction detection. I have seen custom control boxes for linear actuators that look remarkably like a power window controller, which provides end of travel detection via current threshold.

Something like this explains the concept:
http://www.fieros.de/en/projects/window.html