Page 399 - Programmable Logic Controllers, Fifth Edition - Mobile version

L1 Inputs Ladder Logic program Outputs L2
PB_10s
<Local:1:I.Data.1> MOV
PB_10s Move PL_1
Source 10000
Dest T1.PRE
10000

PB_15s
PL_2
<Local:1:I.Data.2> PL_2
MOV
PB_15s Move
Source 15000
Dest T1.PRE
10000
Timer_Start
<Local:1:I.Data.3> TON
Timer_Start TIMER ON DELAY EN
Timer T1
Preset 10000 DN
Accum 0
PL_1
T1.TT <Local:2:O.Data.1>

PL_2
T1.DN <Local:2:O.Data.2>

Figure 15-91 MOV instruction used to create a variable preset timer.

Combining Math, Comparison, • The BCD_Display board monitors the decimal
and Move Instructions setting of the BCD_ TWS.
• The MOV instruction is used to move the data
Combining math, comparison, and move instructions (in the form of BCD) from the BCD_TWS to the
provides a PLC with the ability to perform more complex BCD_Display.
operations. Figure 15-92 shows a PAC Logix program • The setting of BCD_TWS is compared to the deci-
designed so that the BCD_Display displays the setting of mal reference number 20 (BCD 100000) stored in
the BCD_TWS (thumbwheel switch). Both the MOV and Source B of the EQU instruction.
EQU instructions form part of the program. The operation
of the program can be summarized as follows: • The EQUAL_ PL output is energized whenever
the PL_Equal_Sw is true (closed) and the

Inputs Ladder logic program Outputs
L1 MOV L2
Move
Source BCD_TWS
PL_Equal_Sw 2#0000_0000_0000_0000_0000_0000_0010_0000 Equal_PL
Dest BCD_Display
2#0000_0000_0000_0000_0000_0000_0010_0000
PL_Equal_Sw Equal_PL
BCD_TWS <Local:1:I.Data.0> <Local:2:O.Data.0>
EQU BCD_Display
(All 16 bits) Equal
Source A BCD_TWS (All 16 bits)
2#0000_0000_0000_0000_0000_0000_0010_0000
Thumbwheel switch
Source B Source_B
2#0000_0000_0000_0000_0000_0000_0010_0000
0 0 2 0 0 0 2 0
Decimal 20 Decimal = 100000 BCD Decimal
Figure 15-92 Monitoring the setting of a thumbwheel switch.

380 Part 5 Math, Comparison, and Move Instructions

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