4.2.3 Voltage Levels & Current Drive
The output voltage level on PIN 3 (“DATA”) of the DIN
connector is capable of driving one TTL load. The voltage
swing will be a full five (5) Volts instead of the typical TTL
voltage of four (4) Volts. The serial word will be in negative
logic for the printer (positive logic for the EEPROM). In
negative logic, a logic ‘ONE’ will be between 0.0 and 0.8
Volts and a logic ‘ZERO’ will be between 2.4 and 5.0 Volts.
The output line is capable of ‘sinking’ 1.3 milliAmps, and of
‘sourcing’ much more than 100 microAmps, which conforms
to the one TTL load requirement. The inverted Request to
Send line (“RQSNDNOT”) on PIN 1 of the DIN connector
will initiate transmission of the data string when pulled to a
voltage below +0.8 Volts, provided that the Chip Select line
“CSDM” is also low.
4.2.4 Word String Format
The ILT1400 sends out a string of serial words
(characters) to transfer the displayed data to other
equipment, such as a printer or computer. The interface
sends out exactly twelve (12) characters to portray the line
of data. The first character is a ‘+’ or ‘-’ sign for the
mantissa. The second character is the first digit of the
mantissa. The third character is a decimal point. The
fourth, fifth, and sixth characters are the remainder of the 4
digit mantissa. The seventh character is the lower case letter
‘e’ to separate the mantissa from the exponent. The eighth
character is a ‘+’ or ‘-’ sign for the exponent. The ninth and
tenth characters are the 2 digit exponent. The eleventh
character is a carriage return. The twelfth character is a line
feed.
ASCI
I
Decima
l
He
x
Binar
y
LF
10
0a
0 0 0 0 1 0 1 0
CR
13
0d
0 0 0 0 1 1 0 1
+
43
2b
0 0 1 0 1 0 1 1
-
45
2d
0 0 1 0 1 1 0 1
.
46
2e
0 0 1 0 1 1 1 0
0
48
30
0 0 1 1 0 0 0 0
1
49
31
0 0 1 1 0 0 0 1
2
50
32
0 0 1 1 0 0 1 0
3
51
33
0 0 1 1 0 0 1 1
4
52
34
0 0 1 1 0 1 0 0
5
53
35
0 0 1 1 0 1 0 1
6
54
36
0 0 1 1 0 1 1 0
7
55
37
0 0 1 1 0 1 1 1
8
56
38
0 0 1 1 1 0 0 0
9
57
39
0 0 1 1 1 0 0 1
e
101
65
0 1 1 0 0 1 0 1
4.2.5 Plug and Cable Requirements
We offer the A510 25-pin, A512 Serial Adapter, and the
A511 9-pin RS232 Adapter Cables as
optional
accessories to
the ILT1400 to facilitate easy connection of the ILT1400 to
a serial device such as a printer or computer. Please contact
one of our sales representatives for ordering information
It is also possible to use one of the many commercially
available Serial-to-USB adapters to interface the ILT1400 to a
USB printer or the USB port of a computer. (requires A511 sold
seperately)
4.2.2 Character Format
The 20 bits that make up each character word are
comprised of 1 start bit, 8 data bits, and 11 stop bits. The
extra 10 stop bits provide a necessary delay to allow the
microprocessor to perform its other duties. Thanks to
crystal control, the length of a single character (before the
stop bit) is exactly 7.5 milliseconds, followed by a stop bit
delay of exactly 9.17 milliseconds. The following diagram
shows the voltage waveform for the serial character format
of the number “5”. The binary number is transmitted in
reverse order, from least to most significant digit. The most
significant digit is always a binary zero (+ 5 Volts), which
ensures a negative leading edge to the first stop bit.
Содержание ILT1400
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