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6
M2256-000-00-051
November 2001
RS232 Interface
The RS232 communication between the PC and the A75 has the following parameters which
are fixed in the A75 firmware.
For every byte sent, there are 10 bits sent including the start and stop bits:
• Number of data bits = 8
• Parity = none
• Number of start bits = 1 (set to ‘1’)
• Number of stop bit = 1 (set to ‘0’)
The RS232 D-Range socket at the rear of the T201X radio has the following configuration:
Note: The start and stop bits are removed by the A75 for the over-air transmission of data. The FFSK
data sent is pure binary 8 bit data only.
Compatibility
T201X Radio Firmware
When programming the T201X radio firmware for use with the A75 and CCDI, use version 3.01
or greater.
T2000 PGM
When the A75 modem board is fitted, the T201X PGM program settings have the following
constraints:
• ‘BCD Channel Selection’ should be enabled and polarity set to Normal so that the A75
can change the channel with the GO_TO_CHANNEL command.
• Economy mode reduces the radio’s power consumption when it is idle. When economy
mode is active and there has been no valid activity on a channel for the duration of the
economy mode timer, the radio begins economy cycling. This means that the beginning
of a transmission may be lost if it is received after a period of inactivity.
If ‘Economy mode’ is enabled in a T201X with an A75 fitted, set the default Transparent
mode
If a faster data transfer rate is required, then the Lead In Delay can be reprogrammed as
low as 40 ms, but the Economy mode
must
be disabled.
Connections
Function
Connections
Function
1
Not used
6
Not used
2
RXD
7
RTS
3
TXD
8
CTS
4
Not used
9
Not used
5
GND
Содержание T2000-A75
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