Delta Tau GEO PMAC User Manual

Limit and Flag Circuit Wiring 

The Geo PMAC allows the use of sinking or sourcing position limits and flags to the controller.  The 
opto-isolator IC used is a PS2705-4NEC-ND quad phototransistor output type.  This IC allows the current 
to flow from return to flag (sinking) or from flag to return (sourcing). 

 

 

A sample of the positive limit circuit is shown below.  The 4.7K resistor packs used will allow 12-24V 
flag inputs.  If 0-5V flags are used, then a 1K

Ω resistor pack (RP) can be placed in either RP7 (channel 1) 

or RP8 (channel 2).  If these resistor packs are not added, all flags (

±Limits, Home, User) will be 

referenced from 12-24V. 

 

Connecting Limits/Flags to the Geo Drive 

The following diagrams illustrate the sinking and sourcing connections to a Geo Drive.  This example 
uses 12-24V flags. 

Flag Supply

12-24VDC

24V

0V

Return

Flag

Sinking 

Separate 

Supply

 

Flag Supply

12-24VDC

24V

Return

Flag

Sourcing 
Separate 

Supply

0V