Rotary Encoder Frequently Asked Questions

Dedicated ICs are used on both the sending (driver) and receiving (receiver) sides to transmit signals with higher power. A signal with the inverted polarity of the output signal is output, and the difference is used as the signal (differential output). This is a data transmission method compliant with the EIA RS-422A standard.

Totem-pole, open-collector, and collector-output designs use the potential difference between the signal line and COM as the signal. Therefore, if a noise voltage is applied to COM, the potential difference with the signal line decreases, making high-low detection difficult and increasing the likelihood of transmission errors. In contrast, line driver outputs output a signal with the inverted polarity of the output signal, and uses this difference as the signal (differential output). As a result, the potential difference does not decrease, and line driver outputs tend to be more resistant to noise.

Line driver output circuit

Line driver output signal