I/O WM-01 User Manual - Chapter 1: Introduction
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Manual MWireless Serial Modem.wpd
Chapter 1: Introduction
The Wireless Serial Modems are capable of providing seamless dependable serial communications via
radio transmission. This unit can be used together with other Wireless Serial Modems or paired up with
our distributed I/O REMOTE ACCES products with a radio modem integrated in to it.
These units consists of two boards, a radio modem and a serial interface board. The interface board can
be either RS232, or RS485/422 compatible. The radio is a frequency hopping module that uses a standard
asynchronous serial data stream.
Input Power
The unit requires a externally supplied power and has two options to select from (regulated +5VDC or
unregulated +12VDC). Three terminals labeled +5V, GND, and +12V are provided.
5 Volts DC Regulated
The +5V is not regulated and is fed directly to the VCC circuit. Therefore if +5VDC is supplied to
power the module it must be from a regulated source.
12 Volts DC Unregulated
The +12VDC input has a range of +7V to +18V with an on-board 5V regulator in series with the
line. A optional DC to DC converter is available for lower power consumption when battery
savings or heat dissipation considerations are important.
Warning: The Wireless Modem requires that you supply only +5VDC or +12VDC, but never both.
Serial Connections
RS-232:
If wired “one to one” the DB-9 cable connection follows the standard for RS-232, 9 pin
connections. The connection should be wired as shown in Table 1. A female DB-9 cable should
mate directly to any standard RS-232 host mating connector.
RS-422 full duplex:
The HOST serial connection signal pinouts may vary from one manufacturer to another. The Host
Serial signals should be wired as above in Table 1. RS-422 protocol is provided on the board via
jumper selection (install a jumper in the RS422 position on the 485/422 jumper selection).
RS-485 (two wire) half duplex:
The HOST serial connection signal pinouts may vary from one manufacturer to another. The Host
Serial signals should be wired as above in Table 1. The HOST serial transmit and receive signals
are connected together via jumpers on the board (install jumpers on the RS-485+, RS-485-, and in
the RS485 position on the 485/422 jumper selection).
Termination & Bias
In order to avoid noise and reflections in long lines, a cable with a characteristic impedance of 120S
should be selected and the line should be terminated on both ends with 120S resistors. Termination is
provided on the board via jumper selection (TERM). For short lines (when the propagation of the signal is
less than 4% of the time to transmit a bit), the termination might not be needed