Expansion Interface; Rs232 At/Ttl Serial Interfaces - Psion Workabout MX Service Manual

Expansion Interface

The interfaces built into the Workabout are accessible by plugging in appropriate connectors
or adapters at the top or bottom of the unit.
The top connectors provide RS232 AT and either a TTL-level serial interface or a bar code
wand interface. The TTL-level serial interface can operate CCD barcode scanners or low
power laser scanners.
The bottom connector provides access to the LIF connector for the docking interface,
external power and SIBO serial interfaces.
The serial and barcode interfaces are provided by optional internal peripheral modules.
These are fitted inside the Workabout and plug into an internal expansion connector.

RS232 AT/TTL Serial Interfaces

These are provided by the RS232 AT/TTL peripheral module which provides:
an IBM-compatible RS232 AT serial interface at standard RS232 voltage levels
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
n
200 mA, with a current limit at approximately 250mA
The serial format and the polarity of the TTL-level interface can be programmed using
suitable software programs. The interfaces can be operated at a baud rate of 19,200.
+ Note:- Although both interfaces are present in the module, only one can be configured as
operational at any one time.
The 9-way D-type male RS232 AT interface connector pin allocation is shown below:
Pin No.
1
2
3
4
5
6
7
8
9
(1) The EXON signal is the external wake-up control for the Workabout. If the RS232 AT/TTL
peripheral expansion module is configured correctly, the EXON signal switches on the Workabout
when an RS232 or TTL-level rising edge is applied to this signal. The RS232 AT interface is
enabled by opening port A (see Testing the TTL Interface on page 22 for instructions on how to do
this).
Version 1.0
Signal
Name
DCD Handshake - input
RX Serial Receive - input
TX Serial Transmit - output
DTR Handshake - output
GND 0V
DSR Handshake - input and EXON
RTS Handshake - output
CTS Handshake - input
GND 0V
Confidential - PSION INDUSTRIAL PLC
Workabout MX Service Manual
Remarks
(1)
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