Encoder: Line Driver?

Topic:

• When to use an encoder with Line Driver?

Solution:

Reasons to use an encoder with Line Driver

Driver for long distances

• Longer signal lines are possible
• Often amplification of the signal current
• Steeper signal edges (higher frequencies and better use of signals possible)
• Less overshoot at signal edges

Complementary signals

• For differential signal transmission
• In combination with a line receiver that is located in the control electronics, the signal transmission better protected against electromagnetic interference (EMI)
• Particulary important for positioning applications

Possible combinations of encoder and Line Driver/Receiver

Encoder with Line Driver and controller with Line Receiver

Advantages:

• Signal lines protected against electromagnetic interferences
• Long signal lines possible
• Sufficiently high driver currents
• Steep signal edges

Disadvantages:

• Possible higher costs: need of Line Driver and Line Receiver

Encoder with Line Driver and controller without Line Receiver

Advantages:

• Better signal, steeper signal edges, better defined signal levels

Disadvantages:

• Encoder signals not protected against EMI
• Maximum signal levels in the range of 3.5V to 4.0V (see below Line driver chart)

Encoder without Line Driver and controller without Line Receiver

Advantages:

• Lower costs
• Less cables

Disadvantages:

• Encoder signals not protected against EMI (loss of position information)
• For shorter lines only
• Flatter signal edges