Open source PLC

In industrial applications, controlling relays, servos, solenoids, and the like isn’t just a matter of wiring in an Arduino and plugging in some code. No, for reliable operation you’ll need a PLC – a programmable logic controller – to automate all your hardware. PLCs are usually pretty expensive pieces of hardware, which led [Warwick] to come up with his own. He built two versions, one large and one small that can handle just about any task thrown at them.

Both devices are powered by an ATMEL SAM7S ARM chip running at 48 MHz. The smaller of the two devices has 10 digital inputs, 4 analog inputs, and 8 digital outputs able to sink 200 mA each. The larger PLC has 22 digital ins, 6 analog ins, and 16 digital outputs. Both of these devices have a ton of connectivity with USB, RS-232 and RS-485 ports

Below you can see the large PLC being used as a barcode scanner and as a strange device using compressed air to levitate a ping-pong ball. There’s also a demo of the smaller PLC lighting up some LEDs.

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OpenPLC, for industrial automation to Halloween displays

Stepping out onto just about any factory floor you’ll find complex automatons building anything and everything imaginable. These machines need to be controlled somehow and before the age of computers these manufacturing robots were controlled with relays wired together to produce a multitude of actions. Relays, no matter how reliable and bulletproof the are, can’t be programmed without rewiring the entire machine. Now, factories have programmable logic controllers to take care of their automation tasks.

[Thiago] built his own programmable logic controller and released it as open hardware.Included in the OpenPLC are four 24V inputs, four 24V outputs (two with PWM), 0-10V analog inputs, and USB, SPI, and I2C for programming and expansion.

If you’re building anything from an industrial machine in your garage, or simply want really awesome Halloween (or Christmas) decorations, the OpenPLC can take care of driving all the solenoids, motors, and actuators needed. With the extendable I2C and SPI busses, it’s possible to add a plethora of sensors to bring a project to life.

The OpenPLC is based on an ATMega328 and is compatible with Arduino code. There are a few extension boards for digital and analog IO, as well as Ethernet.

Build your own Programmable Logic Controller

[Q] is an Electrical Engineer who works in an industrial setting. He frequently uses Programmable Logic Controllers at work but had never built one himself. He decided to undertake the project at home and managed to build a PLC that outputs 120V AC or 12 V DC and has optoisolated inputs.

On the circuit board you’ll find an ATmega8 and an EEPROM for extra data storage. Six outputs are controlled by relays since they are able to output either alternating or direct current. There are eight inputs which use optical isolators as buffers to protect the microcontroller.

So what did he end up using this for? It was part of his Christmas light setup last year. The image above shows the PLC in a water-tight electrical box with extension cords running to each of the devices he wishes to control. The example code is what he used on the X-mas setup, but it should be enough of a guide to program this to work with just about any application.

The Energy Detective TED 5000-G teardown

Ted 5000-G Teardown

Before [Steve] realized that it didn’t play nice with his network, he dismantled his Energy Detective TED 5000-G to see what made the device tick. He put together a nice teardown with high-res pictures throughout.  Each component of the TED 5000-G is dissected, with the exception of the current transformers, which he claims are pretty boring anyhow.  The gateway module is particularly interesting as it contains both an Ethernet interface as well as a 802.15.4 radio for wireless communications.  While the device is still a bit expensive at the moment, the gateway module could be useful in projects requiring PLC or ZigBee communications some time down the road, once prices ease a little.

25C3: Power line communication


[Florian] and [Xavier Carcelle] started the day at 25C3 by covering power line communication. PLC technology is not widespread in the US, but has gained popularity in countries like France where it’s included in set-top boxes. PLC lets you create a local network using the AC wires in your wall. The team started exploring PLC because despite being newer technology, it had a few principles that made it similar to old networks. There’s no segmentation in the wiring, which means it behaves like a layer 2 hub. You get to see all of the traffic unlike a switched network. Most power meters don’t filter out the signal, so it’s possible that you might see your next-door neighbor’s traffic on your line. [Florian] reports having seen all the traffic in a six-story building just by plugging in. The wiring also acts as a large antenna so you could employ tempest attacks.

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25th Chaos Communication Congress schedule

The team behind 25C3 has published the first draft of this year’s schedule. The annual Chaos Communication Congress is happening December 27th to 30th in Berlin, Germany. There are plenty of interesting talks already in place. We’re spotting things we want to attend already: The conference starts off with how to solar power your gear, which is followed by open source power line communication. A TOR-based VPN, an open source BIOS, rapid prototyping, holographic techniques, and running your own GSM network are on the bill too.

We’ll have at least three Hack a Day contributors in attendance. Last year featured two of our favorite conference talks: [Drew Endy]’s Biohacking and the MiFare crypto1 RFID crack. We hope to see you there.