Dry Contacts

[mityeltu]

Sadly, the response I get from my boss is typical of a non-managing manager. He gets a sort of quizical expression on his face as though he doesn't understand what I asked, and then proceeds to give me the exact same explanation while speaking slower (I guess he thinks I didn't hear all the words or something).

This is not a phone company circuit. This circuit is being used on an asphalt plant. I am tasked with changing the current circuit design to one using a pic mcu to perform the same functions; however, the available potentials are far more than the pic can handle: 24vdc on up to 480vac.

 

[zbang]

I'd say forget about "wet contacts" (never heard that one, either, and it doesn't make sense anyway) and look at it like this- your box can output switched voltage (from an internal supply), switched ground (to the internal common), or switched nothing (just the relay contacts). They're often called current source output, current sink output, and dry contacts. Since the first two use an existing common point, either the + or ground rail of the PS, they require that plus a single terminal per output. Dry contact outputs required at least two terminals per output.

 

[realolman]

Sadly, the response I get from my boss is typical of a non-managing manager. He gets a sort of quizical expression on his face as though he doesn't understand what I asked, and then proceeds to give me the exact same explanation while speaking slower (I guess he thinks I didn't hear all the words or something).

This is not a phone company circuit. This circuit is being used on an asphalt plant. I am tasked with changing the current circuit design to one using a pic mcu to perform the same functions; however, the available potentials are far more than the pic can handle: 24vdc on up to 480vac.

Your posts aren't much different than what you say your boss does.... there isn't too much of what you are posting that is making any sense to this ol' dunce.

Are you talking about a PLC instead of a pic? What's a mcu?

How could the same circuit, wet, dry, or damp have that wide a range of voltages?

Why don't you just post exactly what is the circuit supposed to do and I'm sure somebody on here will be able to give you some good dirrection? Forget the jargon and the buzz words ...

 

[zbang]

Are you talking about a PLC instead of a pic? What's a mcu?

MCU - Micro Controller Unit
"pic" is a family of micro-controllers from Microchip Tech.

This is embedded controls stuff.

 

[realolman]

That didn't even occur to me.


My goodness.... you can program those things, and can't figure out what somebody's talking about with a set of contacts... still ain't makin much sense to me.

Blink a couple LED's:


#include <p16F690.inc>
__config (_INTRC_OSC_NOCLKOUT & _WDT_OFF & _PWRTE_OFF & _MCLRE_OFF & _CP_OFF & _BOR_OFF & _IESO_OFF & _FCMEN_OFF)
cblock 0x20
Delay1 ; Define two file registers for the
Delay2 ; delay loop
endc

org 0
Start:
bsf STATUS,RP0 ; select Register Page 1
bcf TRISC,0 ; make IO Pin B.0 an output
bcf STATUS,RP0 ; back to Register Page 0
MainLoop:
bsf PORTC,0 ; turn on LED C0
OndelayLoop:
decfsz Delay1,f ; Waste time.
goto OndelayLoop ; The Inner loop takes 3 instructions per loop * 256 loopss = 768 instructions
decfsz Delay2,f ; The outer loop takes and additional 3 instructions per lap * 256 loops
goto OndelayLoop ; (768+3) * 256 = 197376 instructions / 1M instructions per second = 0.197 sec.
; call it a two-tenths of a second.

bcf PORTC,0 ; Turn off LED C0
OffDelayLoop:
decfsz Delay1,f ; same delay as above
goto OffDelayLoop
decfsz Delay2,f
goto OffDelayLoop
goto MainLoop ; Do it again...
end

 

[One-eyed Jack]

MCU - Micro Controller Unit
"pic" is a family of micro-controllers from Microchip Tech.

This is embedded controls stuff.

OK. Can you get I/O cards that are relay outputs? If so they must be rated for the voltage and the current of the device that you wish to control. If that does not work for you just pick a voltage that you like and use it to turn a relay off and on . Said relay will operate your motor starter,shutter motor,valve or what ever. Whatever method you choose at some point you will have to switch on/off at the voltage of the equipment that is already in place.

 

[realolman]

Sadly, the response I get from my boss is typical of a non-managing manager. He gets a sort of quizical expression on his face as though he doesn't understand what I asked, and then proceeds to give me the exact same explanation while speaking slower (I guess he thinks I didn't hear all the words or something).

This is not a phone company circuit. This circuit is being used on an asphalt plant. I am tasked with changing the current circuit design to one using a pic mcu to perform the same functions; however, the available potentials are far more than the pic can handle: 24vdc on up to 480vac.

Well, you are going to have to understand exactly what is wanted. You're going to have to find out on your own.


I don't know offhand, but I doubt those pics can even operate a relay.... you are probably going to have to operate optoisolators in order to operate relays..

Seems to me you are going to have to put this stuff on circuit boards... where are you going to get those?

I think the finding out what circuits or contacts are involved may be the easiest part of the problem.

Why wouldn't you use a PLC so you don't have to deal with stuff on a chip level?

It sure seems like somebody (probably me ) doesn't understand at all whats going on.
.