4-20mA output

Started by davi...@sapo.pt July 19, 2009
Hello group
I'm tryng to use Bx24 in a project that requires that one of the BX
output pins delivers 4-20mA...
Any ideas on how this can be done?
Thanks
Regards

David Mendes

> ... 4-20mA...

Analog or digital? Do you need to send a metered value or a switched
signal? Analog current loops, as I recall, use a 16mA swing,
zero-to-full-scale. Digital is either 4ma or 20mA drawn through the
loop. Also, do you need to supply loop power?

Tom

?

Hi,

Here is a link that sale one RS 232 to current converter for under 32 dollars.

?

http://www.l-com.com/item.aspx?idi81

?

?

Regards,

rosarite

-----Original Message-----
From: d...@sapo.pt
To: b...
Sent: Sun, Jul 19, 2009 12:31 pm
Subject: [BasicX] 4-20mA output

Hello group
I'm tryng to use Bx24 in a project that requires that one of the BX
output pins delivers 4-20mA...
Any ideas on how this can be done?
Thanks
Regards

David Mendes

Hello Tom!
Those are hard questions!
From what I understand, the idea is to put the microprocessor to
simulate the behaviour of an analog 4-20mA sensor...
So, depending on the values received on some certain input pins, the
currente of the output pin should vary from 4-20mA...
Is this possible to do with BX24?
Otherwise, I dont know what you mean by "metered value", "switched
value", "16mA swing"...
Thanks for the quick answer

David M.

Citando Tom Becker :

> > ... 4-20mA...
>
> Analog or digital? Do you need to send a metered value or a switched
> signal? Analog current loops, as I recall, use a 16mA swing,
> zero-to-full-scale. Digital is either 4ma or 20mA drawn through the
> loop. Also, do you need to supply loop power?
>
> Tom
>
David,

I have used the AD420... component for years with great success!
Single unit prices are about $19 per component, but you get what you pay
for.
It requires using 3 BX pins for SPI comm with the chip. Sending it a zero
results in 4mA output. Sending it 65535 results in 20mA output. No need for
calibration. Needs 4 ceramic caps. This is a very good chip.

Let me know if you want to use it, I have lots of software and experience.

Chuck
----- Original Message -----
From:
To:
Sent: Sunday, July 19, 2009 12:31 PM
Subject: [BasicX] 4-20mA output
> Hello group
> I'm tryng to use Bx24 in a project that requires that one of the BX
> output pins delivers 4-20mA...
> Any ideas on how this can be done?
> Thanks
> Regards
>
> David Mendes
>
thanx, chuck, that looks like solving the problem...
What if I want a 0-10V output pin?
Regards

David
Citando PFiX Controls :

> David,
>
> I have used the AD420... component for years with great success!
> Single unit prices are about $19 per component, but you get what you pay
> for.
> It requires using 3 BX pins for SPI comm with the chip. Sending it a zero
> results in 4mA output. Sending it 65535 results in 20mA output. No need for
> calibration. Needs 4 ceramic caps. This is a very good chip.
>
> Let me know if you want to use it, I have lots of software and experience.
>
> Chuck
> ----- Original Message -----
> From:
> To:
> Sent: Sunday, July 19, 2009 12:31 PM
> Subject: [BasicX] 4-20mA output
>> Hello group
>> I'm tryng to use Bx24 in a project that requires that one of the BX
>> output pins delivers 4-20mA...
>> Any ideas on how this can be done?
>> Thanks
>> Regards
>>
>> David Mendes
>>
David,

Read the datasheet. It will do 0-5V, 0-20mA, and 4-20mA. You can use the
0-5V out,
but you'll need an op-amp to drive ANY voltage out. Unity gain for 0-5V and
2xgain for 0-10V.
Digi-Key, Mouser, Newark and others carry the AD420 family. It comes in
24-pin PDIP and SOIC.

Chuck
----- Original Message -----
From:
To:
Sent: Sunday, July 19, 2009 5:27 PM
Subject: Re: [BasicX] 4-20mA output/0-10 V output
> thanx, chuck, that looks like solving the problem...
> What if I want a 0-10V output pin?
> Regards
>
> David
> Citando PFiX Controls :
>
>> David,
>>
>> I have used the AD420... component for years with great success!
>> Single unit prices are about $19 per component, but you get what you pay
>> for.
>> It requires using 3 BX pins for SPI comm with the chip. Sending it a zero
>> results in 4mA output. Sending it 65535 results in 20mA output. No need
>> for
>> calibration. Needs 4 ceramic caps. This is a very good chip.
>>
>> Let me know if you want to use it, I have lots of software and
>> experience.
>>
>> Chuck
>> ----- Original Message -----
>> From:
>> To:
>> Sent: Sunday, July 19, 2009 12:31 PM
>> Subject: [BasicX] 4-20mA output
>>> Hello group
>>> I'm tryng to use Bx24 in a project that requires that one of the BX
>>> output pins delivers 4-20mA...
>>> Any ideas on how this can be done?
>>> Thanks
>>> Regards
>>>
>>> David Mendes
>>>
>>>
>>>
>>>
>>>
>>>
>>>