Pull Up - TTL for PLC or high impedance input
Open Drain - to drive a relay or low impedance input
1. Pull-Up – the pull-up resistor is provided internally. The logical high level is fixed to +5 VDC.
2. Open-Drain – requires the provision of an external pull-up resistor and a voltage supply.
3. The logical high level is determined by the external voltage supply and not limited to +5 VDC.
4. The digital outputs are galvanically isolated from GND power and housing ground but not from each other (same ground for all outputs).
Note
To improve the signal quality and reducing the distortion caused due to line reflections, the line on the receiver
side can be terminated with a Schottky diode to limit possible over- and undershoots.