CCJ4MUNICATI0NS SECTION 6.3
6. 3,3
VER.V09F
HUNTER detects input signals with a "fail safe" characteristic.
Input signals from
-25V to +2.5V are detected as a logical
11
1
11
or the mark state. Signals from +3,5V to +25V are logical
11
0
11
or the space state. On the handshake signals the asserted state
is spacing or logical
11
0
11
e.g. CTS.
To summarise,
Output:
Logical
11
0
11
or spacing
Logical
11
1
11
or marking
Input:
Logical
11
0
11
or spacing
Logical
"1" or marking
Output>
+5V with 4K7 load.
Output<
-5V with 4K7 load.
Input >
+3.5V
Input < + 1.5V
Each input provides a line terminator impedance of 6KB.
INTERFACE POWER CONTROL
Under normal circumstances the serial output interface is
powered down to conserve battery life. The first character
which requires transmission causes the interface to be powered
up. A pause of approximately
2 seconds is allowed for the
interface to settle down and then the character is sent. Further
characters are not affected in this way. Once powered the
interface is latched on until HUNTER is switched off or power
removed using an OUT instruction in either Basic or machine
code.
When the interface is powered up it may cause spurious
characters to appear to be sent out, causing problems with the
receiving system. These may be overcome by powering the
interface, prior to requiring the data, by sending any character
as soon as HUNTER is switched on. A Basic LPRINT command will
achieve this.
Altemati vely, the interface may be controlled as follows:
OUT 132, 1
will tum the interface on and
OUT 132,0
will turn the interface off.
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