Psion Workabout MX, Service Manual

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Confidential - PSION INDUSTRIAL PLC
Workabout MX Service Manual
24 Version 1.0
The 9-way D-type female RS232 AT interface connector pin allocation is shown below:
Pin No. Signal
Name
Remarks
1 GND 0V
2 RX Serial Receive - input
3 TX Serial Transmit - output
4 VCCEXT 5V 200mA max
(1)
5 GND 0V
6 DSR Handshake - input
7 RTS Handshake - output
8 CTS Handshake - input
9 GND 0V
(1) The VCCEXT supply is switched on and off at the same time as the TTL serial port is opened and
closed. The RS232 TTL interface is enabled by opening port D for true data and port G for inverted
data (see
Testing the TTL Interface on page 22 for instructions on how to do this).
RS232 AT Serial/Barcode Interfaces
These are provided by the RS232 AT/Barcode peripheral module which provides:
n
an IBM-compatible RS232 AT serial interface at standard RS232 voltage levels at up to
19,200 baud
n
an RS232 TTL serial interface at 5V TTL levels
n
a 5V nominal (4.7V min.) software switched power supply (VCCEXT) which provides up to
200 mA, with a current limit at approximately 250mA
n
a barcode wand interface with a 5V nominal (4.7V min.) software switched power supply
(VCCEXT) which provides up to 200 mA
The RS232 AT interface serial format can be programmed using suitable software programs
and the barcode interface is provided by a Hewlett Packard HBCR-1612 barcode decoder
device. This allows wands which generate digital signals to be connected directly to the
barcode interface. The barcode interface format can be programmed using software,
although this feature is not used if a Hewlett Packard barcode wand is being used, as the
decoder requires a set format.
+
Note:- Although both interfaces are present in the module, only one can be configured as
operational at any one time.