Microwave Data Systems MDS entraNET 900, System Manual

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32 MDS entraNET 900 System Guide (Preliminary) MDS 05-4055A01, Rev. A
2.5 CONFIGURING THE SERIAL
INTERFACES
2.5.1 Overview
Modes
The transceiver includes an embedded terminal server that provides
serial-data-encapsulation over IP. In this capacity, the entraNET 900
acts as a gateway between serial and IP remotes devices. Two basic sce-
narios come to mine, PC applications using IP to talk to remote devices,
or serial PC applications talking to remote serial-devices over an IP net-
work.
Two types of services are offered by the transceiver—TCP and UDP.
TCP provides a connection-type link, and end-to-end acknowledgment
of data, but with some added overhead. UDP provides a best-effort
delivery service.
Most polled protocols will be best served by UDP services as the pro-
tocol itself has built-in recovery mechanisms (error-correction). UDP
provides the needed multidrop operation by means of multicast
addressing, where multiple remote devices will receive and process the
same poll message. The serial-to-serial example which follows, shows
how to provide multicast services. (
See “Point-to-Multipoint
Serial-to-Serial Application Example” on Page 39 .)
On the other hand, TCP services are best suited for applications that do
not have a recovery mechanism (error-correction) and most have the
guaranteed delivery that TCP provides despite the extra overhead. The
IP-to-Serial example shows how to do this. (
See “IP-to-Serial Applica-
tion Example” on Page 36 .)
Essentially the same data services are available for both serial ports:
COM1
and
COM2
. Note that the transceiver
COM1
port is DCE and
COM2
is DTE. Therefore, if the RTU to be connected is also DTE, then a
null-modem cable will need to be used when connecting to
COM2
.
NOTE:
In the discussion that follows,
COM1
and
COM2
will be treated
alike unless noted. They provide essentially the same data
services.
Configuration
There are several configuration parameters for the Remote Serial
Gateway found under the Serial Configuration Menu of the entraNET
Management System. Note that some of the parameters are not appli-
cable to IP-to-Serial mode. After making changes to the configuration,
you must use the menu’s “Execute Changes” to cause the transceiver to
implement the requested changes.