Data Acquisition Toolbox™

ChannelSkewMode - Specify how channel skew is determined

Description

For simultaneous sample and hold (SS/H) hardware, ChannelSkewMode is None. For scanning hardware, ChannelSkewMode can be Minimum, Equisample, or Manual (National Instruments only). SS/H hardware includes sound cards, while scanning hardware includes most Measurement Computing and NI boards. Note that some supported boards from these vendors are SS/H, such as Measurement Computing's PCI-DAS4020/12.

If ChannelSkewMode is Minimum, then the minimum channel skew supported by the hardware is used. Some vendors refer to this as burst mode. If ChannelSkewMode is Equisample, the channel skew is given by [(sampling rate)(number of channels)]^-1. If ChannelSkewMode is Manual, then you must specify the channel skew with the ChannelSkew property. For some vendors, ChannelSkewMode is automatically set to Manual if you first set ChannelSkew to a valid value.

Notes If you want to use the maximum sampling rate of your hardware, you should set ChannelSkewMode to Equisample.

Characteristics

Usage	AI, Common to all channels
Access	Read/write
Data type	String
Read-only when running	Yes

Values

Advantech

{Equisample}

The channel skew is given by [(sampling rate)(number of channels)]^-1.

Measurement Computing

`{Minimum}`	The channel skew is set to the minimum supported value.
`Equisample`	The channel skew is given by [(sampling rate)(number of channels)]^-1.

National Instruments

`{Minimum}`	The channel skew is set to the minimum supported value.
`Equisample`	The channel skew is given by [(sampling rate)(number of channels)]^-1.
`Manual`	The channel skew is given by `ChannelSkew`.

Sound Cards

{None}

This is the only supported value for SS/H hardware.

Examples

Create an analog input object for an MCC device and add eight channels.

ai = analoginput('mcc',1);
addchannel(ai,0:7);

Using the default ChannelSkewMode value of Min and the default SampleRate value of 1000, the corresponding ChannelSkew value is

ai.ChannelSkew
ans =
  1.0000e-005

To use the maximum sampling rate, set ChannelSkewMode to Equisample.

ai.ChannelskewMode = 'Equisample';
ai.Samplerate = 100000/8;