Acromag AVME9125 Series User Manual Download

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Series AVME9125 VMEbus 6U Analog Input Board
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Start Channel Value Register (Read/Write, 49H)

The Start Channel Value register can be written with a 5-bit

value to select the first channel that is to be converted once
conversions have been triggered. All channels including and
between the start and end channel values are converted. A single
channel can be selected by writing the desired channel value in
both the Start and End Channel Value registers.

The Start Channel Value register can be read or written with 8-

bit data transfers. In addition, the Start Channel Value register
can be simultaneously accessed with the End Channel Value via a
16-bit data transfer. The unused bits are zero when read. The
register contents are cleared upon reset.

Start Channel Value Register

Unused

Start Channel Value

07 06 05

After a data conversion cycle, the internal hardware pointers

are reinitialized to the start channel value. Thus, when
conversions are started again, the first channel converted is
defined by the Start Channel Value register.

End Channel Value Register (Read/Write, 48H)

The End Channel Value register can be written with a 5-bit

value to indicate the last channel in a sequence to be converted.
When scanning, all channels between and including the start and
end channels are converted. A single channel can be selected by
writing the desired channel value in both the Start and End
Channel Value registers.

The End Channel Value register can be read or written with 8-

bit data transfers. In addition, the End Channel Value register can
be simultaneously accessed with the Start Channel Value with a
16-bit data transfer. The unused data bits are zero when read.
The register contents are cleared upon reset.

End Channel Value Register

Unused

End Channel Value

15 14 13

New Data Registers (Read Only, 4AH to 4DH)

The New Data registers can be read to determine which

channels of the Mail Box buffer contain new converted data. A set
bit in the New Data register indicates that the Mail Box buffer,
corresponding to the channel of the set bit, contains new
converted data. A set New Data register bit is cleared upon a read
of its corresponding Mail Box buffer.

The New Data bits are also cleared at the start of all new data

acquisition cycles initiated with the Software Start Convert
command. This is done to avoid mistaking data from an old scan
cycle with that of a new scan cycle.

The New Data registers can be read via 16-bit or 8-bit data

transfers. In addition, the register contents are cleared upon reset.

New Data Register (Read Only, 4BH)

Data Bit

Channel

New Data Register (Read Only 4AH)

Data Bit

Channel

New Data Register (Read Only 4DH)

Data Bit

Channel

New Data Register (Read Only 4CH)

Data Bit

Channel

Missed Data Registers (Read Only, 4EH to 51H)

The Missed Data registers can be read to determine if a

channel’s Mail Box buffer has been overwritten with new converted
data before the last converted value was read. A set bit in the
Missed Data register indicates a converted value corresponding to
the channel of the set bit was overwritten before being read. A set
Missed Data register bit is cleared upon a read of its
corresponding Mail Box buffer.

The Missed Data bits are also cleared at the start of all new

data acquisition cycles initiated with the Software Start Convert
command. This is done to avoid mistaking missed data from an
old scan cycle with that of a new scan cycle.

The Missed Data registers can be read via 16-bit or 8-bit data

transfers. In addition, the register contents are cleared upon reset.

Missed Data Register (Read Only, 4FH)

Data Bit

Channel

Missed Data Register (Read Only 4E)

Data Bit

Channel

Missed Data Register (Read Only 51H)

Data Bit

Channel

Missed Data Register (Read Only 50H)

Data Bit

Channel

Start Convert Register (Write Only, 52H)

The Start Convert register is a write-only register and is used

to trigger conversions by setting data bit-0 of this register to a logic
one. The desired mode of data acquisition must first be
configured by setting the following registers to the desired values
and modes: Control, Timer Prescaler, Conversion Timer, Start
Channel Value, End Channel Value, and Interrupt Vector.

This register can be written with either a 16-bit or 8-bit data

value. Data bit-0 must be a logic one to initiate data conversions.

Start Convert Register

Not Used

Start Convert

D15 to D01

D00

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