Keithley 708B Reference Manual page 185

Section 5: Remote commands
Trigger polarity
The Model 707A or 708A instrument has one external trigger input that was available to accept TTL
level trigger inputs to advance the stored relay setup step.
The Model 707B or 708B instrument allows 14 TTL level inputs through the digital I/O connector to
act as events to iterate through a scan list. The handling of this command is similar to the F0 and F1
DDC commands shown in the table below, except that you must specify [N] as the digital I/O line
polarity you wish to set. For more information, see
Scan trigger polarity
DDC TSP equivalent command
A0 digio.trigger[N].mode = digio.TRIG_FALLING
scan.trigger.channel.stimulus = digio.trigger[N].EVENT_ID
A1 digio.trigger[N].mode = digio.TRIG_RISINGA
scan.trigger.channel.stimulus = digio.trigger[N].EVENT_ID
Matrix ready
The Model 707A or 708A instrument provides a dedicated TTL output for when a channel close or
open operation completes. This output includes the settling time of the specific channel (fixed in
hardware) added to a programmed settling time that could be specified by the user. These commands
are shown in the table below.
Matrix ready polarity
DDC
B0
B1
The Model 707B or 708B instrument does not have a dedicated matrix ready line when the DDC
command compatibility is disabled. However, you can create a TSP function that can emulate the
dedicated hardware matrix ready function onto a digital I/O line. The following examples show you
how to create TSP code functions for channel close and channel open, respectively, that will duplicate
matrix ready functionality for digital I/O bit 10. After including these functions in your script, a channel
close operation is made by calling the function with the channel argument:
chanClose("1A01")
For more information, see
Example: Channel close with matrix-ready functionality
function chanClose(chan)
digio.writebit(10,0)
channel.close(chan)
digio.writebit(10,1)
end
5-24
Models 707B and 708B Switching Matrix Reference Manual
TSP equivalent command
No corresponding command
No corresponding command
Digital I/O port (on page 2-7).
Scanning and triggering
Description
Rising edge on matrix ready
Falling edge on matrix ready
Function accepts valid channels as arguments
Clear the 10th digital I/O bit before the close
operation
Close the channels in the argument
Set the 10th digital I/O bit after the close
operation
End the function
707B-901-01 Rev. A / August 2010
(on page 3-1).
Description
Select falling edge for
scan trigger
Select falling edge for
scan trigger