Keithley 3700 series Reference Manual page 302

Section 9: Instrument Control Library (ICL)
scan.add
Remarks
Details
Also see
9-158
Use this function to specify additional set of channels and/or channel patterns to scan.
These items are appended to the end of the existing scan list that was specified by the
scan.create command. The items in ch_list will be appended and scanned in the order
specified in the parameter list.
If the optional dmm_config parameter is not specified then, the configuration
(dmm.setconfig, dmm.getconfig) associated with that channel or channel pattern will be
used. However, if a dmm_config is specified then, that configuration is used for each
channel or channel pattern specified in a temporary override mode. It does not modify
the assigned configuration of a channel or channel list.
An error will occur if:

a specified channel does not exist.

a specified channel pattern does not exist (slot empty or not on card).

a syntax error exists in parameter string.

an empty parameter string for either parameter.

a specified DMM configuration does not exist.

an analog backplane relay is specified.

a step encounters a forbidden item involved in the step (see details)
The scan list of channels or channel patterns will not be updated if any error occurs
during processing of the command.
If a step encounters a forbidden item involved in the step an error will be generated.
Steps before the error are okay. Steps after the one containing the error (in the same
call) are ignored.
For example:
A forbidden item exists on step 1002. A scan.add('1001:1003'), is called with the
intent of adding channels 1001, 1002 and 1003 to the existing scan list. The code
detects a forbidden item when adding step 1002 and an error is generated. The result of
the scan.add command:
1001 was added to the list
1002 was not added
1003 was not added
Steps added before the scan.add causing the errors are all okay as well.
scan.create (on page 9-160)
Series 3700 System Switch/Multimeter Reference Manual
Document Number: 3700S-901-01 Rev. A / August 2007