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Tiny PLC
Looking for a very small PLC with digital I/O
By Kurt Schneider on 14 January, 2005 - 9:51 am

Does anyone make a PLC that could be mounted on a PCB that is 1 inch square or smaller to control 5VDC devices? All I need is purely digital I/O and some internal timers.

By Mark Bayern on 14 January, 2005 - 3:33 pm

Sounds more like a job for a single chip micro -- have you looked at the Microchip line of microcontrollers?

Also, the Atmel AVR is a nice single chip FLASH controller. It is competitive to the PIC, but I like their product line better. I've succesfully used a GNU (Open source) "C" Compiler ported to AVR. I haven't used it in quite a while though.


By Joe Jansen/ENGR/HQ/KEMET/US on 21 January, 2005 - 7:03 pm

Check out this website: Ladder logic compiler for a PIC microcontroller

--Joe Jansen

By Curt Wuollet on 15 January, 2005 - 9:36 am

They call that a microprocessor and the language, assembler, greatly resembles IL. Seriously. You can also get uPs that you can program in higher level languages. I haven't seen a RLL chip, but it's certainly doable, just little demand. Of course, a $5 uP from the automation folks would be $325 and an oblate spheroid geometry so it would only fit their $100 sockets. See if you can't do what you need with a PIC, a Rabbit or an old Z80. Getting it down to 1 chip is kinda limiting but they are out there.


By Michael Griffin on 15 January, 2005 - 9:38 am

Try a PIC chip or a Basic Stamp. The Basic Stamp is a PIC with a basic interpreter ROMMed in and mounted on a very small daughter board. There are
other daughter board micro-controller solutions as well.

By William Sturm on 15 January, 2005 - 4:20 pm

Cheap (about 20), ladderdiagram programming (included)....

By Malcolm Ritchie on 6 April, 2005 - 2:56 pm

Try a resistor, you could duct tape it to the PCB

By Tomy Zacharia on 17 January, 2005 - 8:56 am

Dear Kurt,
Such devices are known as microcontrollers. As you have to control 5 VDC devices, the same can be done with open collector or TTL outputs. A full
blown PLC might be overkill and very big. The smallest PLC I have seen measured 8x10 cm without the power supply. The specs were 5 vdc 8 nos. DO/DI.

Tomy Zacharia