ADA3400 & ADA3300 Common Features
Programmable Gain with Custom Gain Setting.
The boards feature programmable binary gains of 1, 2, 4, 8, 16, and Gx,
where Gx is a user-configured custom gain setting.
Channel-gain Scan Memory
The channel-gain scan memory lets you sample channels in any order, at
high speeds, with a different gain on each channel. This 1024 x 16-bit
memory supports complex channel-gain scan sequences, including digital
output control. This feature allows you to program the values into the
channel-gain table to control TMX32 analog input expansion boards for
high speed scanning of up to 512 random channels. When digital lines are
not used for this feature, they are available for other control functions.
A skip bit is provided in the channel-gain table to support different sampling rates on different channels. When the skip bit is set on a channel, no A/D conversion is performed on that channel, saving you memory and eliminating the need to throw away unwanted data.
A/D Conversions
The channel-gain scan memory - combined with flexible timing, triggering,
and gating modes - provides exceptional versatility and precision in
performing A/D conversions, such as scanning a photodiode array. You can
configure the boards with internal or external pacer clocks and internal
or external triggers. Conversions are controlled by software command, by
the pacer clock, by using triggers to start and stop sampling, or by
using the sample counter to acquire a specified number of samples.
Conversion Modes
The ADA3400 and ADA3300 can perform high speed conversions on a
single channel, or on
multiple channels using the channel-gain scan memory table. Scan mode
incrementally scans through the channel-gain table, with each trigger
starting a conversion at the channel and gain specified in the current
table entry. In burst mode, a single trigger initiates a scan of the
entire table. At high speeds, this can emulate simultaneous
sample-and-hold. The time between samples is set by the burst clock,
and the time between bursts can be set by a trigger or a pacer clock.
When using a pacer clock to trigger bursts, an external event can trigger
the pacer clock. Use programmable burst to scan the channel-gain table
one time for each trigger. Multiburst lets you scan the channel-gain
table a specified number of times for each trigger.
Trigger Modes
The ADA3400 and ADA3300 supports five trigger and gating modes for precise data
acquisition with respect to external events. You can configure the 3400
through hardware and support software for several modes, including
pre-trigger, post-trigger, about trigger, trigger-to-trigger, and
external gate. Pre-trigger lets you acquire data until a trigger occurs.
Post-trigger, the most common mode of acquisition, starts acquisition as
soon as a trigger occurs. About trigger acquires data both before the
first trigger is received, and continues for a specified number of
samples after a second trigger is received (the number of samples is
set by the sample counter). Trigger-to-trigger acquires data during
the time interval between two triggers. Similar to the trigger-to-trigger
mode, external gating samples the inputs as long as the external trigger
line is high, and stops when it is brought low.
Timer/Counters
The 32-bit pacer clock can be programmed to initiate A/D and D/A
conversions at timed intervals without using processor time to trigger
conversions. The 16-bit burst clock triggers a burst sample whenever it
is in turn triggered externally or by the pacer clock. The 16-bit high
speed sample counter can be used to program the number of samples to be
taken, up to 65536. Five 8254-based, 16-bit timer/counters are
available for user functions.
1024 Sample A/D Buffer & Data Transfer
A 1024 sample buffer provides
an interface between the A/D converter and PC to enhance triggering and
storage capabilities and to maintain data integrity. Store up to 1024
samples, or up to 512 samples - each tagged with its channel-gain
identifier - in the buffer. Data can be transferred from the buffer to
PC memory in one of three ways. DMA supports high speed data transfers
directly to PC memory. Data also can be transferred using the programmed
I/O mode or the interrupt mode. A special interrupt mode using a REP INS
(Repeat Input String) instruction supports very high speed data transfers.
By generating an interrupt when the buffer's half-full flag is set, a
REP INS instruction can be executed, transferring data to PC memory
and emptying the buffer at the maximum rate allowed by the data bus.
Analog Outputs
Two independent 12-bit analog outputs with matched D/A converters are
provided on the ADA3400 and ADA3300. The ADA3400 adds a 1024-sample
buffer which supports high-speed output under Windows™ or DOS.
Using the REP OUTS (Repeat Output String) instruction, the buffer can be
reloaded over and over at high speed for continuous waveform generation.
Or, use the buffer's retransmit feature to load the buffer once and
repeat transmission of the data for repetitive waveform generation.
The output can be updated by software command or by setting up a pacer
clock at the desired output rate. Each output channel is independently
jumper selectable for one of four ranges: -5 to +5, -10 to +10, 0 to +5,
or 0 to +10 volts.
Analog Data Markers
Four high-speed digital input lines, Synchronized to the A/D conversion
rate and stored in the buffer, can be used as a 4-bit data or trigger
marker without interrupting the conversion process. On the ADA3400, four
high-speed digital output lines for each D/A converter are Synchronized
to the D/A conversion rate and clocked out from the buffer along with the
analog output data.
Digital I/O
The ADA3400 features 32 buffered TTL/CMOS compatible digital lines: 16
bit-programmable lines which can be independently set for input or output,
and 16 port-programmable I/O lines. You can set any combination of
lines for I/O, such as 1 input, 31 output; 2 input, 30 output, etc.
The bit programmable lines support RTD's two Advanced Digital Interrupt
modes. An interrupt can be generated when the lines match a programmed
value or when any bit changes its current state. A mask register lets
you monitor selected lines for interrupt generation. Eight
bit-programmable lines and one 8-bit port are available at each
of the two I/O connectors. All I/O lines are equipped with bit
configurable pull-up/pull-down resistors.
The ADA3300 features 16 buffered TTL/CMOS compatible digital lines: 8 bit-programmable lines which can be independently set for input or output, and 8 port-programmable I/O lines. Other digital I/O features are similar to the ADA3400.
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