Keithley 7001, Instruction Manual

Page: 65 / 353

Front Panel Operation
4-16
After leaving the scan layer, operation proceeds into
the channel layer.
Channel layer
NOTE
The channel layer is programmed
from the CHANNEL CONTROL
menu (see paragraphs 4.8.1).
Operation in the channel layer is similar to operation in
the scan layer, except that spacing is controlled by
channel events rather than scan events, and the Output
Trigger is always enabled.
When Timer channel spacing is selected, the first chan-
nel will be scanned immediately. Each additional chan-
nel is then scanned at a rate determined by the pro-
grammed timer interval (1msec to 99999.999 seconds).
With Immediate channel spacing selected, channels
will be scanned immediately. The scan rate will prima-
rily be determined by the internally set relay settling
time and any user programmed delay (see paragraph
4.7.4). For Model 701X series cards, the internal relay
settling time is 6msec; 3msec after the relay closes and
3msec after the relay opens. The user programmed de-
lay is in addition to the relay settling time.
The device action (scan channel) for each channel in-
cludes:
1. If not the first channel in the scan, open the previ-
ous channel and wait for the internal settling delay
to time out.
2. Close the next channel in the scan and wait for the
internal settling delay to time out.
3. Wait for the user programmed delay (0 to
99999.999 seconds) to time out.
The Source Bypass (if enabled) will reset (be in effect)
after the programmed number of channels are
scanned.
The Output Trigger for the channel layer is always en-
abled and occurs after each channel is scanned (device
action). For all channel spacing selections, except
TrigLink, the TTL Output Trigger Pulse is available at
the CHANNEL READY connector. For TrigLink chan-
nel spacing, the Output Trigger functions as follows:
1. If the asynchronous Trigger Link mode is selected,
the TTL Output Trigger pulse will be available on
the programmed Trigger Link output line.
2. If the semi-synchronous Trigger Link mode is se-
lected and the Source Bypass is disabled (Channel
Trigger Control set for Acceptor), the Trigger Link
line will be released (goes high).
3. If the semi-synchronous Trigger Link mode is se-
lected, and the Source Bypass is enabled (Channel
Trigger Control set for Source), the Trigger Link
line will be pulled down low and then released.
See paragraph 4.11 for details on the Trigger Link.
RESET and factory defaults set channel spacing to
Manual, channel count to the scan list length, and
Channel Trigger Control to Source.
Scan list
Scanning channels requires that you understand how
to enter channels for the scan list. In general, a channel
is entered using the keypad. The number keys are used
to enter the slot and channel (row and column for a ma-
trix card). The right cursor key (
) (or ENTER key)
adds a comma (,) which is used as a channel separator
or list terminator. The hyphen key (-) is used to define
a range of channels. Finally, the “M” key is used to en-
ter a channel pattern stored in memory. For details, see
paragraph 4.5.2.
When a channel pattern is scanned, the closed switches
in the pattern will close and remain closed for the du-
ration of the scan. A channel pattern is useful for sup-
plying bias voltages in a test system.
Scan procedure
Perform the following steps to scan channels:
NOTE
Before performing scan operation,
make sure the switching cards that
you are using are properly configured.
The CARD CONFIG menu is used to
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