Sensaphone SCADA 3000 Users manual - Manual (Page 157)

15-1
Chapter 15: Ladder Logic Programming
Chapter 15: LADDeR LOGIC PROGRAmmING
Ladder Logic is one of the languages used to program the SCADA 3000 for control functions.
While the C language is more mathematically capable, it does not handle “On/Off” functions
very well. That’s where Ladder Logic comes in. It is the preferred language for control func-
tions. With C Programming, you write formulas. With Ladder Logic, you build constructs out
of a set of symbols. The ladder symbols and expressions represent the program logic used to
control the machine or process. By putting together the various symbols you can build very
sophisticated control programs. The rules/conventions that dictate how programs can be con-
structed are listed within this section. Listed below are the ladder elements and functions that
are supported in the SCADA 3000. A description of each follows the list. Example programs
are illustrated at the end of this chapter.
Note: Windows NT is required if you plan on writing programs that contain 500
or more instructions.
Ladder Logic Elements Supported
XIC
Examine if Closed
XIO Examine if Open
OTE Output energize
OTL Output latch
OTU Output Unlatch
OSR One shot rising
TON Timer on-delay
TOF Timer off-delay
RTO Retentive timer
CTU Count up counter
CTD Count down counter
RES Reset timer or counter
MOV Move
Comparison Instructions
EQU Equal
NEQ
Not Equal
LES Less than
LEQ Less than or equal
GRT Greater than
GEQ Greater than or equal
Math Instructions
ADD Addition
SUB Subtraction
MUL Multiplication
DIV Division
POW Power