User guide

SATELLINE-3AS NMS / NMS Epic / NMS 869 / VHF

User Guide, Version 1.0

Because the transmission has higher priority than reception normally in industrial systems, the

default value of the

Protocol mode

Basic - TX Priority ON

which fits to most systems directly.

Note:

The diagnostic functions are disabled in the

Basic-TX Priority

mode.

7.3

Basic - Repeater

SATELLINE-3AS NMS operates in a store and forward fashion in the

Basic - Repeater

mode. This

means that the radio modem acts as a repeater station i.e. it first receives a message from the

radio interface, buffers the received data (the maximum size of a message is 1 kB) and after the

reception it transmits the buffered data to another radio modem. Only correctly received, valid

messages are forwarded.

Note:

BASIC - REPEATER

MODE WORKS ONLY IN ONE REPEATER SYSTEMS!

If there are two or more repeater stations on the same radio frequency, a message will be

bouncing between the repeater stations forever in an infinite loop. Instead, addressing must be

used in systems that include more than one repeater, in order to prevent such situation and

ensure that a message finally reaches the intended radio modem. The

Advanced - Master

and

Advanced - Slave

modes must be used in those cases - see the next two chapters.

In case a radio modem is in the range of both - original transmitter and the repeater - units, it

will receive a message twice. In other words the duplicate messages appear on the serial

interface. Terminal equipment can be also connected to the serial port of the repeater station. If

the radio modem is already receiving a message to be forwarded, the data coming

simultaneously from the serial port will be buffered until the store-and-forward procedure has

been completed.

The store-and-forward procedure will be completed before transmitting any data - even in the

case that the radio modem has received new data from the radio, while TX Delay is already

activated and it expires in the middle of the store-and-forward procedure. The use of TX delay

together with the Basic - Repeater mode should be avoided without a special reason.

Note:

The diagnostic functions are disabled in the

Basic-TX Priority

mode.