DATA and SETup Commands

Acquisition Data Description

Acquisition Data Description

The acquisition data section consists of a variable number of bytes depending on the number of cards in the configuration, the acquisition mode, and the state tag setting. The data is grouped in rows of bytes with one sample from each pod in a single row. The width of the row is based on the number of cards in the system. Each card has four pods with two bytes of data per pod.

The clock pod data (four bytes) is always first in the data row. The first two bytes of the clock pod data are unused. The total number of bytes in a data row for the various card count configurations is:

Cards

Clock Pod Bytes

Data Bytes

Total Bytes Per Row

1

4 bytes

8 bytes

12 bytes

2

4 bytes

16 bytes

20 bytes

3

4 bytes

24 bytes

28 bytes

The sequence of pod data within a row is the same as shown above for the number of valid rows per pod. The number of valid rows per pod can be determined by examining bytes 253 through 256 for pod pair 3/4 of the master card and bytes 257 through 260 for pod pair 1/2 of the master card. The number of valid rows for other pod pairs is contained in bytes 213 through 252.

A one-card configuration has the following data arrangement (per row):

<clk pod 1> <pod 4> <pod 3> <pod 2> <pod 1>

A two-card configuration has the following data arrangement (per row):

<-----

expansion card ------

><-------

master card--------

>

<clk 1><pod 4><pod 3><pod 2><pod 1><pod 4><pod 3><pod 2><pod 1>

A three-card configuration has the following data arrangement per row:

<- high

expander

-><-lower

expander

-><---

master card---

>

<clk 1><pod 4>.

. .<pod

1><pod 4>.

. .<pod

1><pod 4>. . .

<pod 1>

If the data block is unloaded without first using the DBLock command to specify UNPacked data, this data block description does not apply.

Unused pods always have data, however it is invalid and should be ignored.

17–11