Re:mbbiDirect bits access

[ishita bhatia <ishita3006@gmail.com>]

Hello,

The device I am using is VME and I am currently reading the data from that device via asyn record. The string we are receiving from asyn record is stored in waveform record. Then we are converting data into hexadecimal using scalcout record.After that we have used mbbiDirect record to get values in binary.Now how should are further access the individual bits i am getting from mbbiDirect.

On Mon, Jun 29, 2015 at 7:47 PM, Mark S. Engbretson <Engbretson@anl.gov> wrote:

Ishita Bhatia -

I think that the question that various people want answered is why you
require the data to even be in some sort of array. EPICS has been in use for
decades now, and it is very common to talk to Digital IO hardware,
programmable logic arrays, or other devices where you have a handful or
thousands of elements of binary data - however, before now, no one has
really found it necessary to use arrays for this.

For the most part, this has been because many of these inputs are totally
standalone (example: the status "Open/Close" of a valve) or only have
meaning as a group (example: a filter box with attenuators, the meaning is
not any particular filter, but how they all work together.)

That is why Mark and Ralph want to know what your hardware is, how many bits
you are talking about, what that data actually represents, and why you want
to access it as an array.

You may be making a very simple matter more complicated. Or perhaps what you
want to do might make everyone else say "Why didn't we think of that
before"?

-----Original Message-----
From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov]
On Behalf Of Mark Rivers
Sent: Monday, June 29, 2015 7:37 AM
To: ishita bhatia
Cc: EPICS Tech-Talk
Subject: RE: UCHAR to BitArray conversion(binary-bits array)

As Ralph said, this is still not clear.  Please answer the following:

- What device are you reading from?
- How are you currently reading the data from that device?  By a custom
driver/device support, via asyn record, via streamDevice, etc.
- How do you want to access the data?  Over Channel Access from a CA client,
in some of your own C or Python code, etc.

Typically in EPICS we don't put 32-bit binary values into any array we put
them into a single 32-bit integer and then use a "mask" to select which bit
to access.

Mark

________________________________
From: ishita bhatia [ishita3006@gmail.com]
Sent: Monday, June 29, 2015 12:32 AM
To: Mark Rivers
Cc: Ralph Lange; EPICS Tech-Talk
Subject: Re: UCHAR to BitArray conversion(binary-bits array)

Hello Mark,
As u have asked in previous post, my end goal is to get reading of OPTO card
in form of binary (1's and 0's) where  1 would represent ON status and 0
would represent OFF status. That is why the data which I am receiving from
waveform record(data type: Uchar), I want that data in form of  Binary.
Now as I want data in form of binary, I passed the output of waveform record
in mbbiDirect but the output I am getting from mbbiDirect is in form of 1
binary bit at a time....but I want output as array of binary bits(32 binary
bits as output of my waveform record contains 4 bytes). So please tell me
how to get such output or which record should I use to get that output.
I hope I am making my point clear.