Probe

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Modified by Admin on Sep 13, 2017

Parent Page: Objects

A Probe.

Summary

A probe is a design directive. It is a special marker which is placed on a schematic sheet to identify nodes for digital simulation during netlist generation. It can also be used to interrogate the status, in real time, of a net connecting to a pin on a programmed FPGA device.

Availability

Probes are available for placement in the Schematic Editor only, by choosing Place » Directives » Probe [P, V, R] from the main menus.

Placement

After launching the command, the cursor will change to a cross-hair and you will enter probe placement mode. Position the cursor over a wire or other net object and click or press Enter to effect placement.
Continue placing further probe directives or right-click or press Esc to exit placement mode.

Additional Placement Actions

Press the Spacebar while in placement mode to rotate the probe directive. Rotation is anti-clockwise and in steps of 90°.
Press the X or Y keys while in placement mode to flip the probe directive along the X-axis or Y-axis respectively.

Any changes made to object properties during placement will cause the default properties for the object to be updated, unless the Permanent option - on the Schematic - Default Primitives page of the Preferences dialog - is enabled. When this option is enabled, changes made will affect only the object being placed and subsequent objects placed during the same placement session.

Non-Graphical Editing

The following three methods of non-graphical editing are available:

...via an associated properties dialog

This method of editing uses the following dialog to modify the properties of a probe directive.

The Probe dialog.

The Probe dialog can be accessed prior to entering placement mode, from the Schematic Default Primitives page of the Preferences dialog (Tools » Schematic Preferences). This allows you to change the default properties for the probe directive, which will be applied when placing subsequent probe directives.

During placement, the Probe dialog can be accessed by pressing the Tab key.
After placement, the Probe dialog can be accessed in one of the following ways:

double-clicking on the placed probe directive
selecting the probe directive and choosing Properties from the right-click pop-up menu
choosing the Change command from the Edit menu and then clicking once over the placed probe directive.

...via the SCH Inspector panel

The SCH Inspector panel enables you to interrogate and edit the properties of one or more design objects in the active document. Used in conjunction with appropriate filtering, the panel can be used to make changes to multiple objects of the same kind, from one convenient location.

...via the SCH List panel

The SCH List panel allows you to display design objects from one or more documents in tabular format, enabling you to quickly inspect and modify object attributes. When used in conjunction with the SCH Filter panel, it enables you to display just those objects falling under the scope of the active filter - allowing you to target and edit multiple design objects with greater accuracy and efficiency.

Graphical editing

This method of editing allows you to select a placed probe directive directly in the workspace and change its location graphically. Probe directives are fixed with respect to their size and shape. As such, editing handles are not available when the probe directive is selected:

A selected Probe.

Click anywhere inside the dashed box and drag to reposition the probe directive as required. The probe directive can be rotated or flipped while dragging.

If you attempt to graphically modify a probe object that has its Locked property enabled, a dialog will appear asking for confirmation to proceed with the edit.
If the Protect Locked Objects option is enabled in the Schematic - Graphical Editing page of the Preferences dialog (Tools » Schematic Preferences), and the Locked option for this design object is enabled as well then this object cannot be selected or graphically edited.
You will have to double click on this locked object directly and disable the Locked property or disable the Protect Locked Objects option to graphically edit this object.

Notes

For an FPGA design, the status of FPGA device pins can be monitored directly from the schematic sheet by placing a probe directive on any net that connects to an FPGA pin, as illustrated in the image below.
placing a probe directive on any net that connects to an FPGA pin.

For this feature to function, the source FPGA design must be downloaded to the physical FPGA device and the associated pin states panel for that device must be open and remain open.
The pin states panel for a physical device is accessed by clicking the Show Pins Panel button on the associated instrument panel for that device. The latter is loaded into the Instrument Rack - Hard Devices panel upon double-clicking the entry for the device, in the Hard Devices chain of the Devices view.