PRELIMINARY
Document type: Title: Revision date: Revision:
User's Manual (MUT) Mod. V1729 4 Channel 12 Bit Sampling ADC 22/06/2005 3
NPO: Filename: Number of pages: Page:
00109/04:V1729.MUTx/03 V1729_REV3.DOC 38 28
4.6 Interfaces
4.6.1 VME interface
The board is compatible with the A24-D16 and A32-D32 modes. It supports the h09,
h0B, h0D, h0F, h39, h3B, h3D and h3F ADDRESS MODIFIERS, and therefore deals
with the accesses in block mode.
The base address is given by : switch_address x h10000 (0<switch_address<hFF
for A24-D16 and 0<switch_address<hFFFF for A32-D32)
The offset is given by: sub_address x h100
The complete address is given by : base_address + offset
The IRQ3 is used to signal to the acquisition system the presence of data waiting in the
RAM. This interruption should be released by any writing at the address of the
INTERRUPT register, which sets it back to 0. It is anyhow also reset by the START_ACQ
command.
The sending of IRQ3 can be inhibited by the positioning at 1 of the INH_IRQ bit (bit 1 of
the CONTROL_REG register).
The presence of waiting data can be equally detected without treating the interruption,
but by scanning the presence of a 1 in the same INTERRUPT register. However, it
should be avoided because it is a source of noise during the data acquisition.
The reading of the data stored in the RAM is executed by realizing N successive
readings at the address of RAM_DATA or by realizing series of readings in block mode
at this same address (blocks of 128 16-bit words or 64 32-bit words maximum to comply
with the VME standard).
4.6.2 GPIB Interface
The V1729 boards can have an address set between 0 and 29 (decimal).
Writing
The GPIB commands are carried out by writing a string of characters in the board
situated at the address designated by the rotary switches.
The ASCII code of the first character corresponds to the sub-address of the order to be
executed or of the register to be addressed.
The ASCII codes of the following characters correspond to the data (only one data byte
except in the case of a writing to the sub-address hFF).
Reading
A method of reading by block was implemented to accelerate the reading by GPIB. The
reading of an element is thus executed in the following way :
* Writing operation of the 4 characters (#FF)(#LSB)(#MSB)(#REG) with
(#FF) : ASCII hFF code character
(#LSB) : ASCII code character corresponding to the 8 lowest significant bits of the
number of bytes to read (nbyte).
(#MSB) : ASCII code character corresponding to the 8 most significant bits of the number
of bytes to read.
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