Transponder/Encoder troubleshooting

For encoder units I've seen, their open collector outputs ground the signal
for a logic 1.

Cheers
Pete
Europa builder.

wrote in message
...
Ron Natalie wrote:
: It could go either way... it's just a matter of convention.
: *Usually*, a logic value of '1' means high voltage, and a '0' means
: ground.

: I'm specifically talking about encoders, NOT open collector outputs in
: general. All the ones I am familiar with ground on the logic 1.

If this is true, then it implies negative assert, no? If it's
grounded=='1', then that's opposite convention. Not saying it's not
true, but that makes (troubleshooting) sense.


: Yes, the encoder is
: open-collector outputs, but the reason for diodes is to isolate
multiple
: devices connected to it.

: The diodes may or may not be required depending on what the devices
: interface looks like. Believe me, I've had tons of crap in repeaters
tied
: to a single open collector transitor for the COS and there were no
diodes
: present.

It's not for isolation when all the devices are on, but rather for
when one of them is off. If there's more than one device hanging off a
single encoder, then they must all be isolated. Otherwise, turning off
the transponder could pull all the lines low, and kill the encoder signal
for the GPS as well.

-Cory



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