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3
Operation
3-1
3.1
Introduction
The information in this section is organized as follows:
• Power limits — Covers the maximum power limits of
the Model 7020 Digital I/O Interface Card.
• Channel status display — Summarizes how the main-
frame display is used to provide status of input and out-
put channels.
• Channel assignments — Reviews how I/O card chan-
nels and mainframe slots are designated for channel and
scan lists.
• Controlling output channels — Explains how to open/
close and scan output channels from the front panel.
• Reading input channels — Explains how to read input
channels from the front panel.
• IEEE-488 bus operation — Summarizes the commands
used to control output channels and read input channels
from over the IEEE-488 bus.
The following information pertains to the Model 7020 Digi-
tal I/O Interface card. It assumes that you are familiar with
the operation of the Model 7001/7002 mainframe.
If you are not familiar with the operation of the mainframe,
refer to the Model 7001 or 7002 Instruction Manual after
reading the following information.
3.2
Power limits
To ensure proper operation and prevent damage to the card,
never exceed the following power limits.
Output channels:
Maximum User Supplied Pull-Up Voltage: 25V.
Maximum Sink Current:
Per channel: 65mA
Per bank: 500mA (see note).
Per card: 1A.
NOTE
A bank refers to the internal IC that is used
to drive eight output channels. The card
uses fi e driver ICs (banks) to accommo-
date the 40 output channels. The channels
are grouped as follows for each bank:
Bank 1 = Channels 1 through 8
Bank 2 = Channels 9 through 16
Bank 3 = Channels 17 through 24
Bank 4 = Channels 25 through 32
Bank 5 = Channels 33 through 40
As specified, the maximum output current for each 8-bit
bank (i.e. channels 1 through 8) is 500mA.
Input channels:
Maximum Voltage Level: 42V peak.
3.3
Channel status display
The Model 7001 has a channel status display (Figure 3-1)
that provides the real-time state of each input or output chan-
nel. The left portion of the display is for slot 1 (Card 1), and