Yaskawa PLC-5 - Manual (Page 22)

GENERAL OPERATION
19 Sample PLC Ladder Diagram 5/2/95- RD 3196-10
Figure 10. Sample PLC Ladder Diagram
ABBREVIATION KEY
DSD_INT = Drive network interface to the PLC.
DSDTOPLC = Data transferred from the drive to the PLC.
DSDTOPLC_OLD = Temporary storage of DSDTOPLC for detection of changes in value.
LOAD_PLC = True indicates the value stored in the PLC is to be transferred to the drive.
PLC_DATA = Data to be moved into the PLCTODSD register when the LOAD_PLC bit is true.
PLCTODSD = Data transferred from the PLC to the Drive.
LOAD_PLC —MOV—————————
0 ——| |—————————————————————————————–———— Move — —–
Source: PLC_DATA
0
Dest: PLCTODSD
0
————————————
—NEQ——————– —MOV—————————
1 – Not Equal (A<>B) —————————————————————————– Move — —–
A: DSDTOPLC Source: DSDTOPLC
0 0
B: DSDTOPLC_OLD Dest: PLCTODSD
0 0
—————————–- ———————————–-
Data Moves to
DSD_INT
CW C_W —BTW———————————————
2 ——————| / |———————– | / |——————————–- .Block Transfer Write –—(EN)—–
EN EN Mod Type: 1771-??
Other BLK XFER Module –—(DN)
Rack: 2
Group: 0 –—(ER )
Module: 0
Control Block: CONTROLWORD
Data File:
PLCTODSD
Length: 64
Continuous: N
——————————————————–
—MOV————————–
3 ————————————————————————————————————– Move — —–
Source: DSDTOPLC
0
Dest: DSDTOPLC_OLD
0
————————————
Data Reads from
DSD_INT
C_W CW —BTR———————————————
4 ——————| / |———————– | / |——————————–- Block Transfer Read –—(EN)—–
EN EN Mod Type: 1771-??
Other BLK XFER Module –—(DN)
Rack: 2
Group: 0 –—(ER )
Module: 0
Control Block: CONTROL_WORD
Data File:
DSDTOPLC
Length: 64
Continuous: N
——————————————————–
5 ———————————————————————————–————————————————————-(END)—