S600+ Instruction Manual 
Revised July-2017  I/O  4-7 
Note:  You must connect the feed lines (such as pin 17 on SKT-B) to a 
24 Volts dc source. The DIGIN lines (such as pin 13 on SKT-
B) expect typical “open collector” (referenced to GND) 
connections. 
 
Figure 4-9. Digital Input Schematic (Open Collector Device)  
 
Figure 4-10. Digital Input Schematic (Relay)  
Table 4-4. DIGIN Pin Connections for SKT-B