User guide
SATELLINE-3AS NMS / NMS Epic / NMS 869 / VHF
User Guide, Version 1.0
30
5
SERIAL INTERFACE
The radio modem is referred to as DCE (Data Communication Equipment) whereas the PC is
referred to as DTE (Data Terminal Equipment). The 15-pin female ‘D’-type connector of the
radio modem contains the connections required to establish data communication between the
radio modem and DTE.
The radio modem contains two separate serial ports, which are designated
Port 1
and
Port 2.
One and only one of the ports at a time can operate as the DATA port for user data, while the
other port can be used as the NMS port for the diagnostics interface to SATEL NMS PC
software.
The user can select which one of the serial ports operates as the DATA port or NMS port by
configuring the radio modem in the
Programming Mode
or by using the LCD interface.
The physical interface of the serial ports is as follows:
•
Port 1
complies always with the RS-232 standard.
•
Port 2
can comply either with the RS-232, RS-422 or RS-485 standards. The user can change
the
Port 2
interface type in the
Programming Mode
or by using the LCD interface.
The handshaking signals apply to the selected DATA port. The handshaking signals are CD
(Carrier Detect), RTS (Ready To Send), CTS (Clear To Send), DSR (Data Set Ready) and DTR
(Data Terminal Ready). The physical level of these signals is always RS-232. See the chapter 5.6
Handshake lines
for additional information.
5.1
RS-232 interface
RS-232
standard defines the method of serial data transfer between a computer and its
peripherals. The definition includes both the interface type and signal levels. Most computers
and peripherals contain one or more RS-232 type serial ports. The RS-232 standard uses
transmission lines, in which each single signal line level is referenced, to a common ground
level. RS-232 has been designed to be use in serial transfer of data in situations where the
distance between communicating equipment is less than 15 m.
The otherwise useful RS-232
standard is applied in a multitude of slightly differing ways, (e.g. different pin configurations) and
for this reason different computers and peripherals are not necessarily directly compatible with
each other (see also Chapter 14.2 for more information on RS-232 wiring).
NOTE!
WHEN THE MODE PIN (PIN 12 OF THE D-CONNECTOR) IS GROUNDED, THE RADIO
MODEM IS IN THE PROGRAMMING MODE AND P
Port 1
(PINS 7, 9, 11) IS IN ACTIVE
USE!
If you normally use P
Port 2
for data transmission, the serial cable must be changed to a
standard
(
direct
)
serial cable when switchin
g
over to the confi
g
uration mode.