:DIFF Subsystem

Instrument:

N1000A

DCA-M

Flex Apps:

FlexDCA

FlexRT

Meas. mode:

Scope

Eye

Jitter

TDR

Waveform type:

Differential

The DIFF subsystem commands control differential electrical waveforms. To identify a differential waveform in the :DIFF SCPI command string, you include a single number followed by a single letter. For example, the following command is applied to a module that is installed in slot 3 and the differential waveform from channels A and C as the inputs:

:DIFF3A:COLor TCOLor8

An easy way to see differential channel specifiers in action is to use FlexDCA's SCPI recorder.

Differential waveforms are identified by the combination of module slot number (from 1 to 8) and a letter that identifies the differential channel. The differential channel's letter identifier is the channel that occurs alphabetically first between the two differential input channels. For example, if the differential input waveforms are from channels 3A and 3B, then the differential waveform would be identified as "3A". If the differential input waveforms are from channels 3C and 3D, then the differential waveform would be identified as "3C".

Single-slot modules can have two channels. In this case, the differential waveform of a module installed in slot 4 would be identified as :DIFF4A. Also, when FlexDCA is configured with a simulated extended module, one-slot simulated modules are available that have two channels. The following table show several examples of differential waveform identification.

Traditional modules take up two module slots, either slots 1 and 2 or slots 3 and 4. For these type of modules, the differential waveform is identified using the number for the left-most occupied slot. For example, :DIFF1A or :DIFF3A, respectively.

Examples of Differential Waveform Numbers
Module Type	Installed Slots	Source Channels for Differential Waveform	Differential Channel Waveform Identification
Simulated or Single-Slot, Dual Channel	1	1A and 1B	`:DIFF1A`
	2	2A and 2B	`:DIFF2A`
	3	3A and 3B	`:DIFF3A`
	4	4A and 4B	`:DIFF4A`
Traditional Two-Slot, Dual Channel (for example, 86112A)	1 & 2	1A and 2A	`:DIFF1A`
Traditional Two-Slot, Dual Channel (for example, 86112A)	3 & 4	3A and 4A	`:DIFF3A`

Example Command Sequence

:DIFF1A:DEMODe ON
:DIFF1A:DISPlay ON
:CHANnel1A:BANDwidth BANDwidth3
:CHANnel1B:BANDwidth BANDwidth3
*OPC?