| Non-Voltage Signals Signals where the switch simply turns ON/OFF without an output voltage. To use as a pulse signal, a voltage must be applied to the circuit to detect current flow. Signal sources include contacts and open collectors (shown on the right). |
Contact Signals (Dry Contact) Signal sources using electrical contacts include reed switches, relays, and mercury switches. Dry signal sources using FETs are also available.  |
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| Open Collector Signals Using a transistor with an open collector instead of electrical contacts produces the same effect. Note that current direction differs between PNP and NPN (see right diagram). |
NPN Open Collector |
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PNP Open Collector |
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| Solid State Relay (SSR) | ||
| Voltage Pulse Signals | Zero-Cross Signals Signals that cross the 0V reference potential (positive/negative). This includes various AC waveforms from AC tachogenerators, sine-wave encoders, and electromagnetic flowmeters.  |
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| Logic Signals | ||
| Logic IC Capable of sourcing or sinking current. 5V is the standard voltage. |
Totem-Pole Output |
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Complementary Output Example of an unbalanced output circuit |
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| Line Driver Signals Balanced signals used to avoid the effects of transmission noise (also called differential or balanced signals). They output logic signals of opposite polarity. A balanced input circuit is required on the receiver side. Provides stable operation over relatively long distances.  |
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| NPN Transistor Voltage Output Similar to open collector output, but with a circuit where voltage is applied via a resistor. Known as "Pull-up Output" because the collector voltage is pulled up in the positive direction.  |
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| Semi-Open Collector Signals A convenient open collector signal that combines the advantages of both non-voltage and voltage signals, without being affected by the receiver-side voltage. This unique format was originally pioneered by COCORESEARCH.  |
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| Speed / Ratio | Angle / Position / Total | Flow Rate | Torque / Mixing Ratio | Gear Measurement |