MITSUBISHI ELECTRIC Mitsubishi Programmable Logic Controller QD75D - Manual (Page 713)

Appendix - 71
MELSEC-Q
APPENDICES
BCD (Binary Coded Decimal)
1) This is the abbreviation for "binary coded
decimal", more accurately called a BCD
code. Computers, PLCs, etc., use binary
numbers made up of 1 (ON) and 0 (OFF).
Because this is difficult for humans to
understand, decimal digits are expressed
by a pattern of binary digits. Many of the
digital switches and digital displays used by
humans use a BCD code. The significance
of the bits is shown in the drawing below.
Numbers from 0 to 9,999 can be handled
by 16 bits, and numbers from 0 to
99,999,999 can be handled by 32 bits.
0
B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
4000+1000+800+40+20+10+2 = 5.872
5.872 1 0 1 1 0 0 0 0 1 1 1 0 0 1 0
8
000
4
000
2
000
1
000 80
0
400 200 100 80 40 20 10 8 4 2 1
2) BCD commands are commands in which a
binary number (BIN) is converted to a
binary coded decimal (BCD).
They are used to output data from the PLC
and display it on the digital display.
The following drawing shows a 16-bit
example.
0 BIN code
167
0 0 0 0 0 0 0 1 0 1 0 0 1 1 1
0 BCD code
167
0 0 0 0 0 0 1 0 1 1 0 0 1 1 1
P
o
sitiv
e
/
ne
ga
ti
v
e
163
84
8
192
409
6
2
048
1
024
5
1
2
2
5
6
1
2
8
6
4
3
2
1
6 8 4 2 1
800
0
400
0
200
0
100
0
80
0
40
0
20
0
10
0
8
0
4
0
2
0
1
0 8 4 2 1
BIAS SPEED AT START
A large amount of torque is required when the
machine starts moving, but the torque may be
unstable at speed 0 with stepping motors.
Therefore, movement can be smoothly carried
out by starting the movement at a given speed
from the beginning. The bias speed at start is
the speed set at that start.
Full speed
Speed 0
Bias speed
BIN (Binary)
1) A binary number, more accurately called a
binary code.
All values are expressed as a binary
number in which 1 turns the PLC, etc.,
electricity ON, and 0 turns it OFF. The
significance of the bits is shown in the
drawing below. In the MELSEC PLC, the
highest order bit (B15) is used to indicate
handling as a positive No. (0), or negative
No. (1), so the 15 bits from B0 to B14 are
valid.
0
B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
128+32+4+2+1=167
167 0 0 0 0 0 0 0 1 0 1 0 0 1 1 1
2 15 2 14 2 13 2 12 2 11 2 10 2 9 2 8 2 7 2 6 2 5 2 4 2 3 2 2 2 1 2 0
Posi
ti
ve/
negati
v
e
16
38
4
=
81
92=
40
96=
20
48=
10
24=
512
=
256
=
128
=
64
=
32
=
16
=
8
=
4
=
2
=
1
=
2) BIN commands are commands in which a
binary coded decimal (BCD) is converted to
a binary number (BIN).
They are used to input the data shown on
the digital switch to the PLC.
The following drawing shows a 16-bit
example.
0 BCD code
167
0 0 0 0 0 0 1 0 1 1 0 0 1 1 1
0
BIN code
167
0 0 0 0 0 0 0 1 0 1 0 0 1 1 1
Posi
tive/
nega
tive
80
00
40
00
20
00
10
00
80
0
40
0
20
0
10
0
80 40 20 10 8 4 2 1
1
638
4
819
2
409
6
204
8
102
4
5
1
2
2
5
6
1
2
8
6
4
3
2
1
6
8 4 2 1