Triggered Read From File (Communications Blockset)

Read from a file, refreshing the output at rising edges of an input signal

Library

Controlled Sources sublibrary of Comm Sources

Description

The Triggered Read From File block reads a new record from a file only at the rising edge of the input trigger signal. The output is a sample-based signal.

Note The triggered behavior of this block is one difference between this block and Simulink's From File block. However, the From File block is useful for reading platform-independent MAT-files.

The file can be an ASCII text file, a file containing integer or floating point numbers, or a binary file (in the format of the C fwrite function). The file must be either in the current working directory on the MATLAB path.

When a rising edge of the input trigger signal is detected, this block reads from the file a record whose length is specified in the parameter Output vector length. The first reading always occurs at the first rising edge. After that, if the Decimation parameter is a positive integer k, then the block reads at every kth rising edge. If Decimation is 1, then the block reads at every rising edge.

When the block reaches the end-of-file marker, it either:

Rereads from the beginning of the file, if the Cyclic repeat box is checked, or
Outputs zeros, if the Cyclic repeat box is not checked

If the Data type parameter is ASCII, then the output is an integer. The mapping between decimal integers and ASCII characters is shown below.

Integer
ASCII
Integer
ASCII
Integer
ASCII
Integer
ASCII

0
NUL
32
SP
64
@
96
\

1
SOH
33
!
65
A
97
a

2
STX
34
"
66
B
98
b

3
ETX
35
#
67
C
99
c

4
EOT
36
$
68
D
100
d

5
ENQ
37
%
69
E
101
e

6
ACK
38
&
70
F
102
f

7
BEL
39
`
71
G
103
g

8
BS
40
(
72
H
104
h

9
HT
41
)
73
I
105
i

10
LF
42
*
74
J
106
j

11
VT
43
+
75
K
107
k

12
FF
44
,
76
L
108
l

13
CR
45
-
77
M
109
m

14
SO
46
.
78
N
110
n

15
SI
47
/
79
O
111
o

16
DLE
48
0
80
P
112
p

17
DC1
49
1
81
Q
113
q

18
DC2
50
2
82
R
114
r

19
DC3
51
3
83
S
115
s

20
DC4
52
4
84
T
116
t

21
NAK
53
5
85
U
117
u

22
SYN
54
6
86
V
118
v

23
ETB
55
7
87
W
119
w

24
CAN
56
8
88
X
120
x

25
EM
57
9
89
Y
121
y

26
SUB
58
:
90
Z
122
z

27
ESC
59
;
91
[
123
{

28
FS
60
<
92
\
124
|

29
GS
61
=
93
]
125
}

30
RS
62
>
94
^
126
~

31
US
63
?
95
_
127
DEL

Integer	ASCII	Integer	ASCII	Integer	ASCII	Integer	ASCII
0	NUL	32	SP	64	@	96	\
1	SOH	33	!	65	A	97	a
2	STX	34	"	66	B	98	b
3	ETX	35	#	67	C	99	c
4	EOT	36	$	68	D	100	d
5	ENQ	37	%	69	E	101	e
6	ACK	38	&	70	F	102	f
7	BEL	39	`	71	G	103	g
8	BS	40	(	72	H	104	h
9	HT	41	)	73	I	105	i
10	LF	42	*	74	J	106	j
11	VT	43	+	75	K	107	k
12	FF	44	,	76	L	108	l
13	CR	45	-	77	M	109	m
14	SO	46	.	78	N	110	n
15	SI	47	/	79	O	111	o
16	DLE	48	0	80	P	112	p
17	DC1	49	1	81	Q	113	q
18	DC2	50	2	82	R	114	r
19	DC3	51	3	83	S	115	s
20	DC4	52	4	84	T	116	t
21	NAK	53	5	85	U	117	u
22	SYN	54	6	86	V	118	v
23	ETB	55	7	87	W	119	w
24	CAN	56	8	88	X	120	x
25	EM	57	9	89	Y	121	y
26	SUB	58	:	90	Z	122	z
27	ESC	59	;	91	[	123	{
28	FS	60	<	92	\	124	\|
29	GS	61	=	93	]	125	}
30	RS	62	>	94	^	126	~
31	US	63	?	95	_	127	DEL

Dialog Box

File name: The filename, including its extension, as a string.
Data type: The data type. Choices are ASCII, binary, float, and integer.
Decimation: A decimation factor. If it is 1, then the block reads at every rising edge.
Output vector length: The vector length of the block's output.
Cyclic repeat: Specifies whether to cycle continuously through the contents of File name or to output only zeros after reaching the end-of-file marker.
Threshold in detecting trigger signal: The threshold for the rising edge of the trigger signal.

Pair Block

Triggered Write to File

See Also

To File (Simulink)

Tanh Nonlinearity Triggered Write to File