34
XII.
APPENDIX
A
RS232C HARDWARE INTERFACE
There are three interface options currently available for the
Pachette 2
: (1) printer
interface, (2) data transfer interface, and (3) IrDA interface. Utilization of one or more
of these options requires a hardware interface to the
Pachette 2
. An RS232C standard
serial interface is provided for the printer and data transfer options. A 25-pin D-Type
female connector is located on the rear panel of the
Pachette 2
. This connector has the
following pin out assignment.
PIN
NAME
EIA NAME
FUNCTION
1
FG
AA
Frame
ground
3
TD
BA
Transit
data
2
RD
BB
Receive
data
7
SG
AB
Signal
ground
20
DTR
CD
Data terminal ready
The
Pachette 2
is configured as a Data Communication Equipment (DCE) device as
defined by the RS232C specification. This means that data leaves the
Pachette 2
on pin
3 and enters the
Pachette 2
on pin 2 of the interface.
A third signal active in the interface is Data Terminal Ready (DTR). This is an input to
the
Pachette 2
that, when active, indicates that the interface is ready to accept data
from the
Pachette 2
. When the signal is deactivated by the receiving device, the
Pachette 2
will temporarily suspend data transmission until the DTR goes active again.
This allows slower devices, such as printers and personal computers, to “hold-off” data
transmission from the
Pachette 2
until they are ready to receive the data.
When the
Pachette 2
is attempting to transmit data across the RS232C interface and
DTR remains inactive for more than 30 seconds, the message “NO INTERFACE
DETECTED” will appear on the front panel display, the alarm will sound, and the
transmission will be aborted. This is usually an indication that the interface is not
plugged in, or that the printer is not “on-line”.
All signals within the interface are RS232C standard loads and
±
10V levels. All other
pins on the connector have no connection.