re: Generic GPIB interface proposal

[Mark Rivers <RIVERS@cars3.uchicago.edu>]

Hi folks,

I like most of Gerry's suggestions for the fields in a generic GPIB record.
For consistency with the other generic records (CAMAC, VME) I would like to
propose changing some of the field names.

> gpib.MSG        The place for the application to put bytes
> 		that are to be written and get bytes that
> 		have been read.  Note:  the driver should
> 		consider these bytes as binary data.  Even
> 		null bytes are allowed.  (There could be a
> 		WMSG and an RMSG, but that doesn't seem
> 		needed.)

I think this should simply be the VAL field (which will be a buffer, as in
waveform and other records).

> gpib.CNT      When reading, the number of bytes requested.
> 		If zero, read until an EOI or the EOS
> 		terminator.  When writing, the number of
> 		bytes to be written.  (There could be a
> 		WCNT and RCNT  ...)
> 
> gpib.ACNT       The number of bytes actually transferred in
> 		a read or write, including any terminator.

I would propose that .CNT be renamed .NUSE, .ACNT be renamed .NACT. There
should also be a field .NMAX which defines the maximum buffer size allocated
at record initialization time.

> gpib.PROC       An enumerated list of actions to take.  Writing a
> 		value to this PV is what initiates the data transfer.
> 		Possible values are:
> 
> 		    READ  - addresses device to talk, reads
> 			bytes, sends UNT (untalk).
> 
> 		    WRITE - addresses device to listen, writes,
> 			sends UNL (unlisten).
> 
> 		    SERIAL_POLL - addresses device, sends SPE
> 			(serial poll enable), read status
> 			byte, sends SPD (serial poll disable)
> 			and UNT.

I don't think the .PROC field (which is a standard record field) can be
redefined. I would suggest calling this field .TMOD (for Transfer MODe), which
is what it is called in the CAMAC record.

____________________________________________________________
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