Stages (S Data type)
Stages are used in RLL
PLUS
programs to create a
structured program, similar to a flowchart. Each
program stage denotes a program segment. When
the program segment, or stage, is active, the logic
within that segment is executed. If the stage is off,
or inactive, the logic is not executed and the CPU
skips to the next active stage. (See Chapter 7 for a
more detailed description of RLL
PLUS
programming.)
Each stage also has a discrete status bit that can be
used as an input to indicate whether the stage is
active or inactive. If the stage is active, then the
status bit is on. If the stage is inactive, then the
status bit is off. This status bit can also be turned
on or off by other instructions, such as the SET or
RESET instructions. This allows you to easily
control stages throughout the program.
Special Relays (SP Data Type)
Special relays are discrete memory locations with
pre-defined functionality. There are many different
types of special relays. For example, some aid in
program development, others provide system
operating status information, etc. Appendix D
provides a complete listing of the special relays.
In this example, control relay C10 will energize for
50 ms and de–energize for 50 ms because SP5 is a
pre–defined relay that will be on for 50 ms and off
for 50 ms.
Remote I/O Points (GX Data Type)
Remote I/O points are represented by global relays.
They are generally used only to control remote
I/O, but they can be used as normal control relays
when remote I/O is not used in the system.
In this example, memory location GX0 represents
an output point and memory location GX10
represents an input point.
DL205 User Manual, 4th Edition, Rev. B
3–40
Chapter 3: CPU Specifications and Operations
1
2
3
4
5
6
7
8
9
10
11
12
13
14
A
B
C
D
ISG
S0000
Start S1
JMP
SG
S
0001
P
resent S2
JMP
Part
X1
X0
S6
JMP
Present
Part
X1
SG
S0002
Clamp
SET
S3
JMP
Locked
Part
X2
S400
Wait forStart
C
heck for a Part
Clamp the part
S500
JMP
C10
OUT
SP5
SP4: 1 second clock
SP5: 100 ms clock
SP6: 50 ms clock
Y12
OUT
X3 GX0
OUT
GX10
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