Systems Engineering Associates, Inc.

Systems Electronics Group, Inc.
14989 W. 69th Avenue Arvada, CO 80007
Tel: (303) 421-0484
Fax: (303) 421-8108
Program Structure

The SYSdev programming language is a combination of ladder, high-level (subset of "C") and assembly (MCS-96). All the files which comprise a SYSdev program are programmed in the same language format. Each file can be written in any combination of the language types. The typical M4500 PLC program consists of the following files:

  1. Initialization file (optional): executed once at power up.
  2. Main Program file (required): scanned continuously.
  3. Timed Interrupt file (optional): executed once every 0.250 to 65.000 milliseconds as set by the user.
  4. User Function file (optional): up to 100 user defined subroutines which can be called from any of the above files.
  5. Input Interrupts (ufunc00 and ufunc01): If the input interrupts are enabled, user function 00 is called when IN0 is activated, user function 01 when IN1 is activated.
Each file is executed sequentially from beginning to end. The main program file is executed (scanned) continuously unless interrupted by the timed interrupt or either of the input interrupts. When this occurs, main program execution is suspended while the interrupt file is executed. At the completion of the interrupt, program execution resumes at the point in the main program where the interrupt occurred.

Each file is implemented as a series of consecutive blocks. Each block is defined as one of the three programming languages: ladder, high-level, or assembly. Blocks of the different languages can be intermixed as necessary within the file.

For more information download the complete M4500 Program Development Manual.

M4500 Product Line:

General System Features
System Configurations

PLC Section
Interrupt Inputs
Built-in Analog I/O
Diagnostics/Fault Detection

PLS Section
PLS Channel Programming
Advanced PLS Features

Digital I/O Boards
Analog I/O Boards
Communications Boards
Motion Control Boards
Power Supply
SYSdev Program
Development Software

Data Sheets by part number and User's Manuals

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