What is the maximum voltage that can be applied to the logic/pulse input section?

The maximum voltage is up to 24V.
An input/output cable for the GL series (B-513) is required for logic/pulse input. 

ItemDescription
Number of input channels 4 channels 
Input voltage range 0 to +24Vmax (single ground input) 
Threshold level Approx. +2.5V 
Hysteresis Approx. 0.5V (+2.5 to +3V) 

* Logic and pulse inputs are switchable.