John said:
I'm using a Crouzet Mellium 3 PLC. No problems with it.
Do you really need a relay (isolated contact closure) to start the
thing or can you just use a transistor collector switching the PLC
input to ground to do it?
If it's the latter (which is most likely, I think) then all you need
to do is this:
View in Courier:
+------+
+----->|START |
| | |
C | |
TIMER OUT>---[1KR]----B 2N3904 | |
E | |
| | |
GND>--------------------+----->|GND |
+------+
This is exactly what I tried after getting feedback from this fourm. My
problem is that the timer does not share a common ground with the
circuit. The timer is hand-held with a 9vdc battery. I tried
connecting the timer ground to the PLC ground but it does not activate
the transistor. Here is the transistor I'm using:
http://www.radioshack.com/product/i...kw=transistor&kw=transistor&parentPage=search
What am I missing here?
Just to clarify, while the timer has an internal 9v battery, the output
is 5vdc for 30ms. Also, I did not use a 1K resistor between the timer
and the base.
---
Depending on how much current the timer's output can source, you may
have opened the transistor's base-to-emitter junction. You almost
always need that resistor in there to limit the base current to a
safe value.
Also, I downloaded the installation and wiring manual for the
Millennium II (I couldn't find the one for the Millennium 3) at:
http://www.crouzet-usa.com/downloads/millenium/Installation_and_wiring.pdf
and on page 9 they show the various inputs available. The spec
sheet for the Millennium 3 says that the digital inputs available
are contact closure, NPN transistor, and PNP transistor, so I
suspect the way they have them shown connected for the 2 is also how
they should be connected to the 3, except that the 2 shows only
PNPs.
There is one interesting thing, though, and that's that with AC
mains it looks like the only thing that's allowed is contact
closure. Except maybe for that "XT20 local extension", whatever that
is. (analog inputs, maybe?)
Unfortunately, since you're posting to USENET through Google Groups,
you don't have access to alt.binaries.schematics.electronic. (or
_any_ binaries groups) So, if you could scan the page of the
Millennium 3 manual showing the input connections to a web page and
post a link to it that would be immensely helpful in figuring out
what's going on. Also whether it's running off the mains or DC if
it's like the 2.
