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4
Note
Chapter 4 Features and Functions
Digital I/O Operation
Digital I/O Operation
The digital input/output is well-suited for monitoring and controlling
external devices. You may use the built-in digital I/O bits or port (on the
rear panel), one or more digital I/O modules, or a multifunction modules
with a DIO function. In the following context, multifunction modules
refer to those with a DIO function.
•
The built-in digital I/O (control board) consists of four bits which can
be operated either independently as four bit channels (numbered 091
through 094) or as one 4-bit port (numbered 090).
•
The plug-in digital I/O modules and multifunction modules usually
consist of several 8-, 16-, and/or 32-bit ports. These ports can be
operated independently, which means one port can be used for output
operation, while others can be used for input. However, all bits within
a same 8-bit port are dependent. If one bit of a port is used for input
or output operation, then all other bits of the same port can only be
used for the same operation.
For more information about a specific digital I/O module, refer to the
Agilent 3499A/B/C User's Manual (shipped with the instrument) or visit
www.agilent.com.
Digital I/O Configuration
•
Parameters such as flow control mode, control line polarity (PCTL),
flag line polarity (PFLG), and I/O direction line polarity, are all
configured for the plug-in digital I/O modules and multifunction
modules. However, these DO NOT apply to the built-in 4-bit
digital I/O (on the rear panel).
•
The data line polarity of any 8-bit port (or the 4-bit built-in port) can
be configured from the front-panel. However, using the remote
interface, the data line polarity of any ports (8-, 16-, or 32-bit) can be
configured.
•
Data display format of any 8-bit port, binary or decimal (default), can
only be specified from the front-panel. Once specified, the format
applies to all input and output operations on the same port.
•
When the instrument is turned on or reset, the handshake mode is
set to Mode #1 and the polarities of all configured lines are positive.
More information about handshake modes is given starting on
page 86.
84
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