Scan and Blank settings

Microscope needs to be informed when an external scan signals wishes to take control over the scan. For this purpose, two signals are provided to the microscope

• Scan output - a hardware trigger to the microscope to request switch from internal to external scan
• Blank output - a hardware trigger to the microscope to switch off (blank) its display.

In addition, sometimes two or more external scan controllers must be connected to the microscope, but some microscopes provide only one external scan input interface. For this case, the scan controller provides an additional scan input with an automated internal scan switch, which allows for daisy-chain connections. A daisy chain configurations connects all the scan controllers in series, with inactive controllers passing trough the signals directly from scan input to scan output, so that the active scan controller has access via multiple passive controllers to the external scan interface of the microscope.

Change of these settings require access to a number of internal jumpers for configuration - jumpers are the preferred method for configuration if changes in configuration may break compatibility or damage other equipment, and therefore changes are not intended for end users, but for service engineers only. These jumpers are normally configured in production for the intended microscope, and do not require change in the field unless it must be installed or moved to a different microscope type.

Risk of death by electrocution!
The device must be open to gain access to the internal jumpers - follow instructions from the Hardware Reference manual supplied with the hardware.

Further inversion of Scan and Blank signals is possible via the software.

To access the control logic with the Scan Control app, see the Scan and Blank buttons in the Triggers toolbar.

Internally generated signals

This section assumes no connections to the Scan or Blank inputs of the scan controller - for daisy chaining see next section. 

Internally generated Scan and Blank signals are signals generated by the scan controller. As different microscope models require different Scan and Blank signals levels, internal Scan and Blank signals may be configured with individual internal jumpers to

• Ground (GND)
• +5V
• +15V

These are connected as in the schematic below, showing jumper on GND.

As default, the scan controller is expected to output the Scan and Blank signals when active, i.e. when a scan job is running. However, output logic may be inverted in the firmware. For example, if Scan is configured via its jumper for GND, then 

• when a scan job is not running in the scan controller, then 
  • Without inversion, no output
  • With inversion, internal Scan (GND) will be output
• when a scan job is running in the scan controller, then
  • Without inversion, internal Scan (GND) will be output
  • With inversion, no output

If there is no connection to Scan/Blank In and none of these jumpers are selected (GND, +5V or +15V), then there will be no output on Scan/Blank Out.

Externally generated signals

Externally generated Scan and Blank are signals not sourced by the scan controller, but generated by another external scan controller and passed through this scan controller from scan input to scan output as part of a daisy chained configuration. Logic of passthrough may be configured with internal jumpers, see list below, and further logic is added by the Scan and Blank inversion controls.

Internal jumpers for externally generated Scan and Blank signals may be set to

• Shield Ground (Sh. GND)
• Normally Closed (NC)
• Normally Open (NO)

If Shield Ground jumper is used, then external Scan and Blank signals are forced to ground, and passthrough is not activated.  

If Normally Closed jumper is used, then this can achieve daisy-chaining, as illustrated in the schematic inserted below 

• When a scan job is not running in the scan controller, then
  • Without inversion, external Scan and Blank will be output (passthrough)
  • With inversion, internal Scan and Blank will be output
• when a scan job is running in the scan controller, then
  • Without inversion, internal Scan and Blank will be output
  • With inversion, external Scan and Blank will be output (passthrough)

If Normally Open jumper is used as in the schematic below, then external and internal signals are shorted. 

• When a scan job is not running in the scan controller, then
  • Without inversion, no output on Scan and Blank
  • With inversion, Scan and Blank will be output (passthrough)
• When a scan job is running in the scan controller, then
  • Without inversion, Scan and Blank will be output (passthrough)
  • With inversion, no output on Scan and Blank