Page 412 - Programmable Logic Controllers, Fifth Edition - Mobile version

Ladder logic
Count_PB
<Local:1:I.Data.1>
CTU
Count Up CU
Counter C1
Preset 25 DN
Accum 0
PL_1
GRT LES <Local:2:O.Data.1>
Greater than (A>B) Less than (A<B)
Source A C1.ACC Source A C1.ACC
0 0
Source B 5 Source B 10
PL_2
L1 Inputs EQU <Local:2:O.Data.2> Outputs L2
Equal
Source A C1.ACC
0 PL_1
Count_PB Source B 15
PL_3
NEQ <Local:2:O.Data.3>
Not Equal PL_2
Source A C1.ACC
Reset_PB 0
Source B 20
PL_3
C1_DN C1
RES
Reset_PB
<Local:1:I.Data.2>

FBD equivalent

CTUD_01
Sheet 1 of 4 CTUD ... Sheet 2 of 4 GRT_02
GRT ...
Count Up/Down
0 0 Greater Than (A>B)
Count_PB CUEnable ACC ACC
0 ACC 0 Source A
CDEnable DN 2-B2 3-B2
25 1-C2 5 0 BAND_01
25 PRE 4-B2 5 Source B Dest
Reset BAND ...
Boolean And
BOR_01 LES_02 In1 0
BOR ... LES ... In2 Out PL_1
Boolean Or Less Than (A<B)
0
Reset_PB In1 0 Source A 0
Out 10 Dest
In2 10 Source B

EQU_01 NEQ_01
Sheet 3 of 4 Sheet 4 of 4
EQU ... NEQ ...
Equal Not Equal
0 0 0 0
ACC SourceA Dest PL_2 ACC SourceA Dest PL_3
1-C2 SourceB 1-C2 SourceB
15 20
15 20
Figure 15-112 Comparison between ladder logic and the FBD equivalent for a program used to test the accumulated
value of a counter.

Function Block Programming Part 6 393

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