What is it?

CANADUINO MEGA2560 PLC 300-24 V1.3 is equipped with 16 digital inputs (3-24V), 14 relay outputs 250VAC/5A and 8 analog inputs and outputs (0-10V). Its purpose is to control everything you would use a PLC or "Smart Relay" for, from lighting scenes over frequency motor drives to HVAC for a greenhouse.

What is it for?

I worked for years with Panasonic, Siemens, Automation Direct and other PLCs, also with different kinds of "smart relays" like Siemens Logo. The base models, sometimes quite affordable, usually only come with some digital GPIO ports. No analog ports, no serial ports and communication capabilities. When ever I needed 2 analog ports to read a sensor value or to control a frequency drive for a 3-phase motor with a 0-10V or RS232 control, I had to spend hundreds of Dollars in additional modules.

Today's microcontroller platforms are so versatile, cheap and easy to use, that it is quite obvious to use them as core for a simple but powerful PLC. The idea behind this product is, to find the cheapest possible way to make a full-featured PLC happen what is easy to program and to integrate in current installations. There already many Arduino programmable PLCs available, but they all have limited functions if affordable, or they burn a hole in your pocket as soon you ask for all the available features.

This Kit offers a very affordable opportunity to add a programmable logic controller to many kinds of projects and machines like lighting, HVAC, greenhouses, water treatment or smoke houses. It can help you control your Halloween decoration or your manufacturing equipment.

How does it work?

CANADUINO MEGA2560 300-24 PLC uses an Arduino MEGA2560 or compatible module and can be programmed using Arduino IDE. I can also recommend Mitov’s “Visuino” visual programming tool. If you prefer to program it "old school" in the ladder language, you will find programming software as well.

CANADUINO MEGA2560 300-24 PLC fits a very small budget but delivers power and versatility equal to 10x more expensive professional process control devices.

MEGA2560 300-24 PLC basic features:

• 8 analog 0-10V inputs (10-bit res.)
• 8 analog inputs or GPIO (direct Arduino connection)
• 8 analog 0-10V outputs (8-bit res.)
• 2 interrupt inputs
• 16 digital 3-24V inputs (opto-insulated)
• 14 digital 250V/5A relay outputs
• 2 x RS232 serial port (option), 1 x I2C Bus and 1 x SPI

MEGA2560 300-24 PLC is a Do-It-Yourself kit comprising only through-hole parts with a pin pitch of typically 2.54 mm or more and is easy to build using basic electronic tools like soldering station and shear flush cutter.

There are 16 opto-isolated digital inputs, typically recognizing any voltage 3V to 24V DC as HIGH level. This of course depends on the CTR of the opto-isolators and can be differ. The ones we ship with the kit have a typical CTR of 50-200 but can be replaced by a different type, for example with CTR of 400-800, to make the inputs work already with a voltage as low as about 2.5V.

The 14 digital outputs are fast acting relays OMRON G5NB-1A-E with about 10ms operate and release time, and high-capacity contacts. The maximum load can be 5A @ 250VAC or 30VDC.

Analog inputs and outputs on screw terminals are designed for 0-10V operation, typically used for light dimmers or motor drivers, for example.

Several 10V output terminals are available to deliver 10V level for example to a potentiometer, to generate the analog input signal. The 10V level is adjustable in a range of about 9-11V and is also used to drive the output relays. The 10V supply outputs in the analog input section are over current protected (trip point 200mA) by a self-resetting fuse.

I2C bus and SPI are exposed for an easy connection to auxiliary devices, for example to connect to RTC and SD-Card module.

If serial connection is required, 2 serial ports RS232 can be added as option (MAX233CPP). The socket and the D-Sub connector are already included in the base kit. RS232 can be used to connect to machines, frequency motor drives, computers or HMI devices, for example. Both ports are available on the same 9-pin male D-Sub port. Port COM2 is available on pins 2 and 3, while COM3 is available on pins 7 and 8. The 1st serial port is used for programming and monitoring (RX/TX through USB). Only your imagination and your programming skills set the limit.

Note: Arduino MEGA2560 module is not included (but available from UNIVERSAL-SOLDER).

Note: A DIN rail mount (tray) with outer dimensions of 212 x 128mm is available as option and snaps on standard 35mm DIN rails (see product variants).

Note: 2 serial ports RS232 can be added by installing a MAX233CPP chip (available from regular distributors).

CANADUINO MEGA2560 DIY PLC 300-24 Schematic