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IU80 features and LEDs

Signal interpolation

The IU80 divides the 4 micron periodic signals produced by the SP80 by a factor of 200. This gives a system resolution of 20 nm for each probe axis.

Error signal generation

The IU80 monitors the signals received from the SP80 probe to ensure that each axis readhead is functional. In the event of probe cable damage or unreliable probe signals, an error signal is latched and provides an output via pin 4 of the 26-way connector. A red LED on the IU80 front panel also indicates the same error conditions however, the different errors can be distinguished by an operator looking at the different LED states as detailed in the IU80 LED summary section below. The latch can be reset by either pressing the button on the front panel or applying logic ‘1' to pin 3 of the 26-way connector.

Probe present signal

The IU80 will detect if an SP80 probe is connected.

If a probe is present, error signals will be enabled and pin 8 of the 26-way plug will be logic ‘0'.

If a probe is not present, error signals will be disabled and pin 8 of the 26-way ouput connector will be logic ‘1'.

IU80 front panel

The front panel of the IU80 has two LED indicators and a reset button.

The green 'POWER ON' LED is illuminated when power is applied to the IU80.

The red 'PROBE ERROR' LED is illuminated if an error has been detected.

The reset button, when pressed, will clear the error condition.

IU80 LED summary



Permanently off

No error

Permanently on

Probe signal integrity compromised


Cable break detected

In the event of an error signal all measurement should be stopped and the probe recalibrated.