The Axis Positioning Module (APM) is an intelligent,
programmable, single-axis positioning controller integrated into the Series Six Programmable Controller (PC)
system. The APM provides a real time interface between
the Series Six PC and a servo-controlled axis. The user
can monitor and control the APM from a Program Development Terminal (PDT) while the APM performs the
complex calculations required to control a precision servo
system. Due to the complete integration of the APM into
the PC system, the Series Six provides a predictable, yet
flexible, axis control capability. The features and benefits
of the APM are summarized in Table 1.
The Axis Positioning Module resides in a Series Six I/O
rack where it is serviced by the Series Six Central Processing Unit (CPU) in the course of a normal CPU scan.
(Figure 1 provides a view of the module circuit board and
faceplate.) The CPU communicates with the APM via the
Series Six I/O Bus using the standard Series Six protocol.
The APM translates the positioning commands it receives
from the CPU into a position versus time profile, determines the current position of the axis using the input
from an absolute position feedback device (a resolver),
and compares it with the commanded position indicated