+ Reply to Thread
Results 1 to 8 of 8

Thread: How to send 4-20mA (1/3000 resolution)

  1. #1

    Default How to send 4-20mA (1/3000 resolution)

    Hi,

    I am doing a project using BS2 that need to send 4-20mA signal (1/3000 resolution).

    The workflow is: After BS2 receiving input through RS-232 (ASCII), it will send 4-20mA signal.

    I have no problem receiving ASCII data through RS232 and process the ASCII with BS2, but I have zero-knowledge about sending 4-20mA using BS2.

    By browsing this forum, I found that I need DAC (16-bit for 1/3000 resolution). Can I use MAX5661? How to do the wiring between MAX5661 (or any 16-bit DAC) and BS2? How to do the BS2 code?

    Pls help me.....Thx a lot

    Bronson Alex

  2. #2

    Default Re: How to send 4-20mA (1/3000 resolution)

    Is AD421 (DAC 12-bit Serial-interface) suitable for BS2?

  3. #3
    PJ Allen's Avatar
    Location
    Outer Darkness! Charon-Quaoar-Sedna Circuit
    Posts
    5,030
    Blog Entries
    1

    Default Re: How to send 4-20mA (1/3000 resolution)

    Here's a recent Subject that dealt with 4-20mA:
    http://forums.parallax.com/showthrea...highlight=20mA

    Unfortunately, the ascii-art didn't exactly translate with the Forum's migration to its present format (if you copy and paste it into Notepad, it'll probably come right, with Lucida Console.) When it comes to pics I always post Dwgs, text is for text.

    For the DAC'ing, go to the Parallax http://www.parallax.com store site and search for DAC. You'll find links to sample programs, etc., which should provide clues for you if not for your specific device.

  4. #4
    PJ Allen's Avatar
    Location
    Outer Darkness! Charon-Quaoar-Sedna Circuit
    Posts
    5,030
    Blog Entries
    1

    Default Re: How to send 4-20mA (1/3000 resolution)

    Attached is a dwg for a current source (regulator.)
    It's not ascii-art, but it'll have to do.
    Attached Thumbnails Attached Thumbnails Click image for larger version

Name:	4_20mA.jpg‎
Views:	106
Size:	50.7 KB
ID:	72796  

  5. #5

    Default Re: How to send 4-20mA (1/3000 resolution)

    The AD421 should work fine with the BS2. Since it's a loop-powered transmitter, you could even use it with digital isolators between it and the Stamp.

    -Phil

  6. #6

    Default Re: How to send 4-20mA (1/3000 resolution)

    Phil, Could you pls send me the wiring diagram for using AD421?

    Thx

  7. #7

    Default Re: How to send 4-20mA (1/3000 resolution)

    I don't have a wiring diagram. The AD421 datasheet includes the information you need. Aslo, there's a schematic on this page that shows the AD421 connected to a PIC. The connection would be similar for a BASIC Stamp.

    -Phil
    Last edited by Phil Pilgrim (PhiPi); 08-28-2010 at 09:08 PM.

  8. #8

    Default Re: How to send 4-20mA (1/3000 resolution)

    Thanks Phil...
    I will try your suiggestion right away.

+ Reply to Thread

Similar Threads

  1. Make Magazine Pixelmusic 3000
    By Nick McClick in forum Propeller 1 Multicore Microcontroller
    Replies: 7
    Last Post: 08-04-2008, 01:25 PM
  2. The Pixelmusic 3000 on Make 14
    By Giemme in forum Propeller 1 Multicore Microcontroller
    Replies: 2
    Last Post: 05-30-2008, 07:56 AM
  3. Higher FREQOUT resolution or PWM resolution
    By Andy McLeod in forum BASIC Stamp
    Replies: 10
    Last Post: 05-12-2007, 07:47 AM
  4. IP 3000 Processors
    By william chan in forum SX Chips and Programming Tools
    Replies: 2
    Last Post: 07-03-2005, 10:14 AM
  5. 3000 lines of code?
    By Archiver in forum BASIC Stamps Archive
    Replies: 13
    Last Post: 05-24-2002, 10:11 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts