User Manual
Chapter 10
GFK-1742F
Jan 2020
Introduction to Local Logic Programming
246
Chapter 10:
Introduction to Local Logic
Programming
This chapter contains an introduction to the basic local logic programming concepts. The
DSM and the DSM motion programming language are not discussed in detail in this chapter.
These concepts are discussed in other chapters within this manual.
10.1
Local Logic Programming
The local logic program works in conjunction with the host controller logic program and
motion program to yield a flexible programming environment. Specifically, local logic
programs provide the user with the ability to perform math and logic that is deterministic
and synchronized with the DSM Position Loop execution rate. This ability is critical to many
applications where the accuracy and/or speed require this tight synchronization.
The DSM local logic function provides the user the ability to execute basic logic and
mathematical functions within the DSM module. Additionally, local logic permits fast
read/write access to local DSM digital and analog I/O. Consult Chapters 13 and 14 for a
complete listing of available I/O. The local logic program execution method guarantees the
local logic program runs at the position loop sample rate and completes each sample
period. Note: If the module is unable to complete the local logic program execution within
the allotted time the module generates an error message. Chapter 13 and Appendix E
contain more information concerning program execution times. Additionally, the local logic
program runs in parallel with normal DSM motion programs. The parallel program
execution allows the local logic program to supervise the motion program. Thus, local
logic programs are also called supervisory logic blocks (SLB). The local logic program
execution versus motion program execution is shown in Figure 113.
Figure 113: Local Logic Versus Motion Program Execution