5 second reset?
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From: mpm on 13 May 2010 13:46 On May 12, 11:18 am, jodleren <sonn...(a)hot.ee> wrote: > Hi all > > I need to hold Reset on a PLC for some time. > To do so I'd like to use a crystal and chip, not a condensator or > something. > > I looked at the 4060, which has an onboard option for a crystal, but I > am a little uncertain about how the counter works - I need to divide > by at least 160000 (or, say 2 in power of 17 or 18 is just fine for > me). > > Is there a single chip available that can do most of it? > > Present power is either 5 or 12V. > > Sonnich I didn't think of it before, but you can probably also use a line stretcher for this. These devices are commonly used in residential / commercial security alarms to enlongate the signals from fast-acting sensors (like vibration sensors). If the sensors react too quickly, the alarm panel might "miss" the event entirely, hence the need to stretch the signal. They are cheap. Under $10 wholesale. Something like this one: http://www.unitedsecurity.com/Website%20PDFs/710.pdf .....though this particular model might not be the best choice? I've seen some that have adjustable stretch times. Google pulse stretcher. Or of course, the designs offered here will certainly work too if you want to make your own board, etc... If I were going this route, I'd use a PIC, or one of those NXP 8-pin 8051 types. LPC901? Good luck. -mpm
From: JosephKK on 14 May 2010 02:07 On Thu, 13 May 2010 03:20:22 -0700 (PDT), jodleren <sonnich(a)hot.ee> wrote: >On May 13, 8:17 am, shbazjinkens <rossmoff...(a)gmail.com> wrote: >> On May 12, 11:18 am, jodleren <sonn...(a)hot.ee> wrote: >> >> >> >> > Hi all >> >> > I need to hold Reset on a PLC for some time. >> > To do so I'd like to use a crystal and chip, not a condensator or >> > something. >> >> > I looked at the 4060, which has an onboard option for a crystal, but I >> > am a little uncertain about how the counter works - I need to divide >> > by at least 160000 (or, say 2 in power of 17 or 18 is just fine for >> > me). >> >> > Is there a single chip available that can do most of it? >> >> > Present power is either 5 or 12V. >> >> >Sonnich >> >> Is there some reason that the PLC logic can't be modified to >> accommodate your needs? > >Dont know yet. The manufacturer recommends so for this 15+ years old >TNS PLC. > >Sonnich Reset for PLC is so not like reset for uC.
From: John Fields on 14 May 2010 06:54
On Thu, 13 May 2010 11:35:47 -0500, John Fields <jfields(a)austininstruments.com> wrote: >On Wed, 12 May 2010 09:18:15 -0700 (PDT), jodleren <sonnich(a)hot.ee> >wrote: > >>Hi all >> >>I need to hold Reset on a PLC for some time. >>To do so I'd like to use a crystal and chip, not a condensator or >>something. >> >>I looked at the 4060, which has an onboard option for a crystal, but I >>am a little uncertain about how the counter works - I need to divide >>by at least 160000 (or, say 2 in power of 17 or 18 is just fine for >>me). > >--- >The 4060 is a 14 stage binary ripple counter with an on-board >oscillator circuit. > >It works by progressively dividing the input clock by succesively >higher powers of 2 up to a maximum of 16383 clocks, when all of its Q >outputs will be high. > >Then, on the 16384th clock, it'll reset and all the outputs will go >low, starting a new count cycle. >--- > >>Is there a single chip available that can do most of it? > >--- >I don't think so, since it sounds like you'll be using a 32768Hz >crystal for the oscillator and you want a 5 second delay. > >That's 163840 clocks, and a 4060 can only count up to 16383 until it >overflows, but you can easily do it using a couple of 4060s or a 4060 >and a 4024, plus some kind and some glue logic in either case. --- Oops... Two 4060's won't work because the LSBs aren't pinned out, but a 4060 and a 4024 will. |