SWITCHING SIGNAL CHANNELS (SSC)
The Smart Sensor’s internal signals are referred to as Switching Signal Channels (SSC); the external input and output signals that result from an SSC are designated Output Switching Signals (OSS). By default, a Smart Sensor has a single-point threshold SSC enabled on Pin 4 (OSS1) of its connector, which operates in either IO-Link mode or Standard-IO (SIO) mode. On power-up, a Smart Sensor defaults to SIO mode; once the sensor is connected to an IO-Link
master, a ‘wake-up’ pulse from the master switches it to IO-Link mode. Thereafter, bidirectional communication operates between the master and the sensor.
A second SSC may optionally be configured on Pin 2 (OSS2) of the Smart Sensor connector. If enabled, SSC2 operates solely in SIO mode and may be designated as a input or an output channel. The presence of a second IO channel gives integrators access to powerful additional features of the Smart Sensor, including Device-to-Device communication,Teach functions and Built-in Test functions.
DYNAMIC SWITCHING LOGIC
When specifying Contrinex Smart Sensors, designers assign their chosen switching logic to any of the available sensing modes – either as a one-time choice at the time of installation, or dynamically as the equipment operating sequence dictates. A single sensor provides all the options needed to monitor multiple parameters, with the flexibility to make real-time changes over IO-Link or via the built-in Teach function.
With single-point mode selected, Smart Sensors behave as conventional two-state devices. The default logic (which may be inverted if the application requires it) sets the switching signal to “high” (SSC ON), if a
threshold level or setpoint (target sensing distance, for example) has been reached. Either side of the switching point, the signal simply switches between ‘high’ and ‘low’’ accordingly.
Window mode allows designers to monitor a range of values, which may be defined either by two discrete switching setpoints or by upper- and lower-threshold boundaries. As the example shows, the default logic sets the switching signal to
“high” (SSC ON) if the measured value lies between the two setpoints. In all other cases, once the measured value moves outside the defined range, the switching signal is set to “low”.
TWO-POINT (HYSTERESIS) MODE
Two-point (hysteresis) mode showcases the Smart Sensor’s ability to respond to setpoints or threshold values that trigger a change in the SSC only when the measured value is moving in a specified direction (rising or falling). In the
example shown, as the measured value falls and passes SP1, the SSC remains set to ‘low’ (SSC OFF). Only when the measured value reaches SP2 is the SSC set to ‘high’. As the measured value rises again, passing SP2 has no effect on the SSC, which is only set to ‘low’ once the measured value reaches SP1 again.