Arduino + PLC

Hi everyone, i am wondering can i connect arduino to PLC as input and output signal? Here is my idea to connect them together.

https://drive.google.com/file/d/0B5vpg7RgVkbJV2taVlBSM3Vpck0/view?usp=sharing

Is it possible? Or any possible connection wiring?

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http://postimg.org/image/965cjbsht/
This is the clear connection

The Arduino uses 5V IO while a PLC typically uses 24VDC. You can either use a relay in between the 2 or find a PLC that accepts 5VDC IO.

I must say I am having trouble following your sketch.
How do you end up with 10V and 5V?
and what do those circles represent?

Considering:
1. The PLC's I/O voltage appears to be 24V ...AC? ...DC? ....sourcing?
2. An Arduino's max I/O voltage is 5VDC
3. The max voltage to power an Arduino via Vin is 20VDC although a max of 12VDC is recommended

I fail to see how your proposed connections would work.

My take would be to have:
1. A separate power source for the Arduino - either via 5V USB power supply or a 12V wallwart.
2. An interposing 5VDC relay between the Arduino output and the PLC input.

The PLC is clearly 24 Volts, and the Arduino (except the controllino) are only 5 Volts.

two ways to solve this:
make a communication protocol between the PLC and the arduino, have the PLC be the master as this is the slow one. this way you only need a few resistors and only one simple transistor on the arduino.

the simplest way is to have all optocouplers in between, one side on 5 Volt and one side on 24 Volt, all with suitable resistors depending on type of optocouplers. or as ais says use relays (more costly though.

10v and 5v are external DC supply. I just want to power up the arduino with 10V in order to have the similar power of 24V like a battery in series.

Btw, is it just connect the 5VDC relay can solve this problem, the output signal of the Arduino can be sent to PLC? Are there any special wirings in connecting the PLC, arduino and the relay?

ac123 said:

10v and 5v are external DC supply. I just want to power up the arduino with 10V in order to have the similar power of 24V like a battery in series.

Btw, is it just connect the 5VDC relay can solve this problem, the output signal of the Arduino can be sent to PLC? Are there any special wirings in connecting the PLC, arduino and the relay?

Click to expand...

You don't need 2 external supplies - the Arduino can output 5V to drive the relay.
The coil of the 5V relay is connected to the Arduino output.
The Input to the PLC is connected via a set of contacts of the 5V relay.

If you don't want to use a relay, you could also use a BJT + resistors - but then you probably need a PCB to mount it.

This discussion is done many times on arduino.cc forum.
all relais boards need an external power supoply not coming from the arduino.
every coil needs a transistor (or optocoupler) as the output of arduino is max 40 mA. a relais is > 100 mA.

the relaiscontacts can be used directly on the inputs of a PLC. switching 24 Volts to the input.