Digital I/O and Relay board - DR51


Active Member

The Industrologic DR51 is a specialized single board computer that is easy to program and easy to connect to external signals. Its two 10 amp relays, eight logic level I/O signals (with keypad connector), and serial port make it an ideal interface for many industrial control, access control, and home automation applications. It can even be used as a universal keypad encoder and key to RS-232 converter.

Price: $69

I have yet to use anything like this, so I guess my question is; thoughts? Price?


Active Member
Quoted from miked @ proximis forums:
Got the controller in the mail today, and had a chance to play around with it. Overall, I'm very pleased! It's a solid little unit.

There's only one somewhat minor downside, and that is that the Tiny Basic programming language is more limited than I had thought. The instructions say that you're limited to variables A,B,C,D,E,F,G, and that's well enough. But then they give you some examples on conditionals:

IF A<>B 20 ;go to 20 if a does not equal b
IF A=1 30 ;go to 30 if a equals 1

So, I just naturally assumed that other variable conditionals would work, too, like:

IF B=1 20


IF C<>B 30

But no go. The If statement is really an "IF A" statement, as the variable A has to be your first operand. The second operand can only be a number, a string, or the variable B. So no "IF A=C", for instance.

What this does is force you to reserve the variables A and B as sort of registers (which I imagine is exactly what they are -- direct mappings of registers of the proc to BASIC variables). In my application, I am constantly switching out variables C and D for A, so that I can test these variables.

That is, there is no dynamic memory in the controller -- you get a bit of flash mem, for the program, and the 7 registers of the proc, mapped to variables A->G.

So, my only big concern is that, although there's plenty of memory for what I need to do with a single controller, in terms of program size, I may run out of variables to store the status of things, because you really only have five variables, since A and B have to basically be reserved. I've already "used up" C and D, so I have 3 left, E, F, and G. What I will have to do after that is to start using flash mem for the variables, but that adds another layer of complexity.

In all, it's a great little controller -- I just wish it had a *bit* of DRAM!


I have personally used the Kit74, which can be purchased at many sites online. The kit cost me $33 and had 8 (I think) relays. One site I know sells them is and for software I run FFHC, which was designed for the Halloween use, Frightmare Forest Haunt Controller it stands for, however it can be used for anything. I did an animated Christmas display with it last year, using 2 kits and for inputs I used jumpers, no input circuits as the webpage of the software writer shows. I was in on the beta testing of the original, so I'm somewhat biased, but it works well and is easy for beginners to program and use. Check for more information on the software, and Kit74's.