SERIES APZU+ ACROPACK
USER’S MANUAL
Acromag, Inc. Tel: 248-295-0310 -
72
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www.acromag.com
Note 2:
With PCIe we have a header for address and read/write command that is
sent with every packet. This header is 20 Bytes with data payload of 4 Bytes (for our
typical AcroPack). For each 4 Byte data sample, 24 Bytes are sent.
/
=
10.4 M samples/sec or 41.6 M Bytes/sec or 0.332 G bit/sec
Note 3:
For our typical AcroPack have measured back to back 4 Byte read
operations completing every 1.7usec. A read operation starts with a host read
request. The AcroPack must process the read and fetch the data and then
generated the completion back to the host. The host then sends a message back
that says I got it. This back and forth hand shaking slows down individual reads.
Note 4:
DMA Read of 1024 sample takes 100us. Each sample is 4 Bytes.
100us/1024=0.0977us per sample or 4/0.0977us = 40.94Mbyte/s. We use DMA
transfers to improve data transfers on the AP341/2 and AP225/235.
Note 5:
Simple write operations are just as fast as DMA read operations. Write
data is presented to the AcroPack in one transaction. Measured 4-byte back to back
write accesses taking place every 100ns.
