• The channel dialog
• Input configuration

Channels

One of the most important features of Gxsm is the multichannel-capability.

Multichannel-capability describes the simultaneous data acquisition and display from different sources. You may e.g. at the same time measure topography and friction-forces with the AFM.

The channel dialog

Figure: Channel Selector Window

The channel dialog pops up selecting Ch. Sel. in the main window. You can use it, to select the displaymode (View) and the port for data acquisition (Mode) for any channel.

One of the following modes can be chosen:

1. No During data aquisition no data are displayed.
2. Grey 2D The data are displayed as a grayscaled image in an own window.
3. Surface 3D Three dimensional view of your data in an own window.

For acquisition of data several modes are available:

1. Off or On. Off deletes the channel.
2. Active. The most important mode, it sets the active channel. All image manipulation is done using this channel. Only one channel can be Active at a time.
3. Math Channel, which stores the result of the last operation is automatically called Math.
4. X Needed for several math/image-manipulation, that need more than one source. See section (13.4.5).
5. +- Scan Xsm: This channel will be used as a target for a scan. Which data source is used to fill this channel is defined by the following indicator (e.g. topography).

   The toggle +- Scan defines the scanning direction at which data are collected. Thus +Topo means measurement of your topography during movement of your scanhead in +X direction. The +- Scan button toggles this direction.

   Gxsm: In Gxsm the third row has a new button, which indicates the direction, with which data are acquised.

6. Inputchannel, whose names are given by the local configuration (See ). Different data sources are selected here.

Input configuration

In this section the assignment of data sources to the Gxsm channels is explained. This configuratioin is done using the Preferences dialog - section DataAq. The particular configuration depends heavily on your data acquisition hardware and is unique for each instrument.

To give a symbolic name to your input channels you use the x-resources. E.g. Xsm*DataSrcA1: ZForce means, that your first multiplex-(MUX)-channel is given the name ZForce in an AFM-environment. Depending on your needs and hardware, several channels are available.

The PCI32 has four A/D-converters with four input-lines directly connected. The older PC31 has only two A/D-connectors, but four input-lines are adressed via a 4x-multiplexer, which results in eight usable analog input lines. Name convention in the x-resources is A and B for the converters and 1 to 4 for the four multiplexer input lines (PC31).

The PCI32 has four converters which are called A1, A2, A3 and A4.

Scanning Probe Microscopy (SPM) usually has one input variable which is controlled to be constant by the control-loop on the DSP.

Through setting and holding the normal force (ZForce, see above) you gain the topography (Topo) signal in contact-mode-AFM operation.

This name is configurable through the x-resources as well. The entry Xsm*PIDSrcA1: Topo means, that the signal which is acquired from and set to the first multiplexer-input line at the AD-converter A is called Topo.

You can set default multiplex-channels to be active on program start. Simply add , * at the end of any resource entry.

The first three letters of your channel names must be non-ambiguous, because they will be used in your automatically generated filenames. (See also section ).