Keithley 7707, Руководство пользователя

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4. Press SHIFT and then CH OFF to enable the channel. If, for example, you enable channel 112, the following will be
displayed:
SETUP D:112
NOTE
If the channel was configured as an output channel (SETUP message dimmed), it will
automatically switch to an input when it is enabled.
5. Repeat steps 3 and 4 if you wish add another digital input channel to the scan list.
6. With the desired digital input channels added to the scan list, press ENTER and finish configuring the scan.
Scanning — The scan is started by pressing STEP or SCAN. When a digital channel is scanned, the input pattern will be read
and displayed. The selected digital data format determines the type of reading that is displayed (decimal, hexadecimal, or
octal). Example for hexadecimal format:
0xFF D:112 Hexadecimal FF read at input channel 112. The bit pattern for this value is 11111111.
Buffer — This same digital data is also stored in the buffer as each channel is scanned (press RECALL to access data stored in
the buffer). Note that if you change the digital data format, the format for digital readings already stored in the buffer will also
change.
Remote programming
Use the ROUTe:SCAN <clist> command to add digital channels to a scan list. For details, see Table 6 and the command
descriptions that follow the table.
NOTE
For details on all other aspects of scanning, see Section 7 of the Model 27xx User’s Manual.
Digital limit testing
An input channel can be configured to compare the input to a specified 8-bit digital pattern. There are two modes for the
comparison; pattern or mask. When the input is compared to an exact pattern, the limit test will fail for anything but an exact
pattern match. For example, assume the set pattern is 00001111. The digital limit test will only pass if the 8-bit input pattern is
00001111. The limit test will fail for any other input pattern.
When compared to a mask, only 1’s in the mask are used for the comparison. Any 0’s in the mask are treated as “don’t care”
bits. Assume the mask is set to 00001111. When the limit test is performed, the limit test will pass only if the four least
significant bits of the input pattern are 1’s. Examples:
Assume mask = 00001111:
If input = 00001110, the limit test will fail.
If input = 10101111, the limit test will pass.
If input = 11111111, the limit test will pass.
NOTE Like limit testing for analog inputs, there are two sets of limits available for each digital input
channel; Limit 1 and Limit 2. However, for front panel operation, Limit 1 has precedence over
Limit 2. For details on limit testing for analog inputs, see Section 8 in the Model 27xx User’s
Manual.