RIO Remote I/O System User Guide
Installing a Long Distance Module (LDM)
Page 177
Chapter 2 Installing hardware and software
Installing a Long Distance Module (LDM)Introduction
The RIO Long Distance Module (LDM) allows you to extend your RIO sy stem via a leased
line. Using a RIO Long Distance Module you can make connections can over thousands of
miles using synchronous (X.21/X.21bis) or asynchrono us interfaces.
You can increase the number of RTAs on the remote site using standard RIO cables, making
the LDM more cost-effective and more practical than a multipl exer.
The LDM consists of two Long Distance Units (LDUs). Each unit compr ises a converter box
with flying leads as shown in Long Distance Unit main components on page 178. One
LDU connects your local host card or RTA to a modem, the other connects the remote RTA
to a modem. You can configure the speed and protocol using a dial on the LDU.
The LDM also supports twisted-pair RS422 cable up to a distance of 1km. This may provide
a more cost-effective solution than the RIO Fibre Optic Link Ki t in environments with low
interference levels or a low security risk. Alternatively, it could be used to provide fault
tolerant links for a fibre optic link based system.
A typical remote system is shown in the next picture.
Note
The LDM is specifically designed for use on high-speed synchronous connecti ons. Slower,
asynchronous speeds are supported but are only recommended for applicatio ns where low
throughput is acceptable.
LDU
Peripheral,
for example
printer
Modems connected
by leased line
RTA
Host card
LDU