You are not registered yet. Please click here to register!


 
 
plc storereviewsdownloads
This board is for PLC Related Q&A ONLY. Please DON'T use it for advertising, etc.
 
Try our online PLC Simulator- FREE.  Click here now to try it.

New Here? Please read this important info!!!


Go Back   PLCS.net - Interactive Q & A > PLCS.net - Interactive Q & A > LIVE PLC Questions And Answers

Reply
 
Thread Tools Display Modes
Old July 30th, 2004, 03:07 PM   #1
Control Freak
Member
United States

Control Freak is offline
 
Join Date: Jul 2004
Posts: 44
Wink 10 Bit Encoder Decoder/ GE90-30

Anyone have any simple ways to decode the 10 bit grey scale code from an absolute encoder? My customer spec'd this unit and now I get to figure it out. I know some PLC's have decoder functions, however I know very little about them. In this case I'll be using a GE series 90-30 with an IC693APU305 (some processor module), also spec'd by the customer.
Silly me, doing it the easy way with Prog Limit Switches all this time. Way too easy, I suppose.
  Reply With Quote
Old July 30th, 2004, 03:58 PM   #2
Steve Bailey
Lifetime Supporting Member + Moderator
United States

Steve Bailey is online now
 
Steve Bailey's Avatar
 
Join Date: Apr 2002
Location: The boondocks of Western Massachusetts USA
Posts: 8,387
Think of the APU305 as a programmable limit switch module for the 90-30. It can accept absolute encoder input, so there should be no need to decode anything. It's a special version of the High Speed Counter module.

The manual for the module is publication number GFK-1028, available from the GE Fanuc website.

http://www.geindustrial.com/cwc/gefa...IO/s9030-m.htm
  Reply With Quote
Old July 30th, 2004, 04:10 PM   #3
PLucas
Member
England

PLucas is offline
 
PLucas's Avatar
 
Join Date: Apr 2002
Location: Gillingham Kent
Posts: 1,742
Control Freak

I use grey code absolute encoders on our cranes, these input into a GE series six PLC. This is the code I use for decoding our gray scale inputs, I am sure this will translate straight into a 90-30, or be very close.


GREYCODE BINARY
BIT 10 BIT 10
---| |----------------------------------( )


GREYCODE GREYCODE BINARY
BIT 9 BIT 10 BIT 9
---| |-----------|/|-----+--------------( )
|
GREYCODE GREYCODE |
BIT 9 BIT 10 |
---|/|-----------| |-----+

GREYCODE GREYCODE BINARY
BIT 8 BIT 9 BIT 8
---| |-----------|/|-----+--------------( )
|
GREYCODE GREYCODE |
BIT 8 BIT 9 |
---|/|-----------| |-----+

GREYCODE GREYCODE BINARY
BIT 7 BIT 8 BIT 7
---| |-----------|/|-----+--------------( )
|
GREYCODE GREYCODE |
BIT 7 BIT 8 |
---|/|-----------| |-----+

GREYCODE GREYCODE BINARY
BIT 6 BIT 7 BIT 6
---| |-----------|/|-----+--------------( )
|
GREYCODE GREYCODE |
BIT 6 BIT 7 |
---|/|-----------| |-----+

GREYCODE GREYCODE BINARY
BIT 5 BIT 6 BIT 5
---| |-----------|/|-----+--------------( )
|
GREYCODE GREYCODE |
BIT 5 BIT 6 |
---|/|-----------| |-----+

GREYCODE GREYCODE BINARY
BIT 4 BIT 5 BIT 4
---| |-----------|/|-----+--------------( )
|
GREYCODE GREYCODE |
BIT 4 BIT 5 |
---|/|-----------| |-----+


GREYCODE GREYCODE BINARY
BIT 3 BIT 4 BIT 3
---| |-----------|/|-----+--------------( )
|
GREYCODE GREYCODE |
BIT 3 BIT 4 |
---|/|-----------| |-----+


GREYCODE GREYCODE BINARY
BIT 2 BIT 3 BIT 2
---| |-----------|/|-----+--------------( )
|
GREYCODE GREYCODE |
BIT 2 BIT 3 |
---|/|-----------| |-----+

GREYCODE GREYCODE BINARY
BIT 1 BIT 2 BIT 1
---| |-----------|/|-----+--------------( )
|
GREYCODE GREYCODE |
BIT 1 BIT 2 |
---|/|-----------| |-----+





Hope this helps

Paul

P.S I see Steve replied while I was busy typing one fingered
__________________
There are 10 types of people in this world..
Those who understand binary and those who don't!
  Reply With Quote
Old July 30th, 2004, 04:32 PM   #4
Control Freak
Member
United States

Control Freak is offline
 
Join Date: Jul 2004
Posts: 44
Thanks guys.
The parts aren't here yet, but I want to stay ahead of the game rather than playin ketchup. Hopefully the APU unit is as easy to use as it appears. I've never worked with the GE platform at all, so this should prove to be an interesting experience. banghead
John
"there are 10 people..." <--- clever
  Reply With Quote
Old August 2nd, 2004, 12:24 AM   #5
Doug_Adam
Member
Australia

Doug_Adam is offline
 
Doug_Adam's Avatar
 
Join Date: Sep 2002
Location: Perth
Posts: 948
I had this problem a little while ago as well.
Using a truth table I worked out that this converter was a series of XOR gates.
I then found an old text book with the same information in it.
If you notice, PLucas has also given the same answer.

Doug
  Reply With Quote
Old July 12th, 2005, 01:24 PM   #6
Unregistered
Guest
 
Posts: n/a
problem with conversion

I see a small problem with the gray to binary conversion diagram that was drawn out by PLucas. Please correct me if I'm wrong.

The first XOR has to be the next bit of the gray code XOR'd with the first decoded Binary Bit and so on. Like this:


Gray MSB Bin MSB
---||-----------------------()---


Bin MSB Gray Bit6 Bin Bit6
---|/|------||--------------()---
|
Bin MSB Gray Bit6 |
|
---||-------|/|---------

Bin Bit6 Gray Bit5 Bin Bit5
---|/|------||--------------()---
|
Bin Bit6 Gray Bit5 |
|
---||-------|/|---------


And so on.

Hope this helps
  Reply With Quote
Old July 12th, 2005, 01:28 PM   #7
504bloke
Lifetime Supporting Member
England

504bloke is offline
 
504bloke's Avatar
 
Join Date: Jan 2005
Location: Down South
Posts: 2,710
JohnW has a logix 500 attachment for an slc 505 prog here

http://www.plctalk.net/qanda/showthr...ight=gray+code

It may be helpful
__________________
Regards

Dave



"When you are courting a nice girl an hour seems like a second. When you sit on a red-hot cinder a second seems like an hour. That's relativity."
Albert Einstein (1879-1955)
  Reply With Quote
Reply
Jump to Live PLC Question and Answer Forum


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Topics
Thread Thread Starter Forum Replies Last Post
signed and unsigned guest LIVE PLC Questions And Answers 13 September 12th, 2017 02:45 AM
Latch a Bit then Bit Shift Left jthornton LIVE PLC Questions And Answers 2 August 22nd, 2003 08:35 AM
Internal addresses rogerhollingsworth LIVE PLC Questions And Answers 5 August 10th, 2003 08:02 PM
Update/evaluation of internal relays/contacts...PLEASE HELP s_viswesh LIVE PLC Questions And Answers 18 October 14th, 2002 03:58 PM
does the gear box affecting the positioning value???? common LIVE PLC Questions And Answers 3 July 6th, 2002 06:11 PM


All times are GMT -4. The time now is 08:48 AM.


.