Rockwell Automation 4100-IF2 IF2 I/O Interface to PDM Installation Instructions - Manual (Page 6)

6 IF2 I/O Interface to PDM
Publication 4100-IN001A-EN-P- February 2001
Overview
The IF2 I/O Interface to PDM is a printed circuit board intended for
use with the positioning drive modules (PDM).
Figure 1 Front View of I/O Interface Board
These drives are built with output stages which source current to
their loads, and input stages which require a current sinking input to
operate. The 24 volt supply from the drive to the input/output (I/O)
is floating, and if the negative side is connected to safety ground
there is a possibility that an earth fault on a control wire would
cause the I/O to go to an active state resulting in an unexpected
action from the drive. In order to comply with EN60204-1: 1993, it is
necessary to connect the 24 volt positive circuit to ground if any
external control conductors (i.e outside the control enclosure) are
connected to the I/O. This can create compatibility problems with
some programmable logic controllers, and the purpose of this board
is to reverse the polarity of the I/O circuit to remove the problem of
compatibility.