Re: Absolute encoder outputs

On Mon, 05 Oct 2009 10:45:28 -0700, Capt. Skinny wrote:
On Oct 5, 12:41 pm, Rich Grise <richgr...@xxxxxxxxxxx> wrote:
On Mon, 05 Oct 2009 08:21:38 -0700, Capt. Skinny wrote:
I am trying to emulate the single ended output of an absolute encoder
(I have the circuit but not the encoder). The encoder has a pinout
similar to the following:

1  24v supply
2  0v
3  bit 1
4  bit 2
5  bit 3
6  bit 4
7  bit 5
8  bit 6
9  bit 7

The output signal is 5v for high bit, 0v for low bit. I'm not quite
sure how to emulate the encoder's 5v signal to the circuit. Do I use
the signal lines as a sink for a small load @ 5v? If anyone can point
me to some introductory references, it would be greatly appreciated.
Clearly I did not design the circuit, I'm just trying to use it.

You need to know more about the encoder's outputs, and the bit pattern.
Does it say if the encoder outputs are TTL compatible or anything? If it
just says 5V, I'd use HCmos logic at 5V for the outputs, but you need to
know what bit pattern corresponds to what output/input you need.

Here are some
references:http://www.google.com/search?q=basic-electronics-tutorial

Thanks Rich. I have the bit pattern, I just want to toggle individual
bits. I don't know whether the outputs are CMOS or TTL, but encoder's
output sink current is listed as "25mA max". Would my proposed solution
(using the signal lines as a sink for a small [< 25mA] load at 5V) work
for either CMOS or TTL signals? Both or neither? Thanks again.

You might want to use something like the ULN2803 8-section darlington
driver (open-collector) and 1K or so pullups to +5V.

At least that shouldn't blow anything up. :-)

I seem to remember some chips that would sink 25 mA, but at the moment,
I'm drawing a blank. It shouldn't be too hard to research, though.

Have Fun!
Rich

.

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