DAVIS GroWeatherLink Uživatelský manuál stáhnout pdf (Strana 2)

12 - 2 3/1/99

• Fifth, configure the GroWeatherLink software to talk to the remote stations using the repeater. For each

weather station that requires the use of a repeater, you will have to manually specify the connection

address. In the Serial Port Settings dialog, select “Other” as the “Radio Name”. (Also select YDI Model

910 Multi-Point” as the connection type.) You will then enter the connection string in the “Phone” field

in the “Modem Settings” part of the dialog. The basic form of the connection string is: <remote ID>

“via” <repeater1 ID>”,”<repeater2 ID>.

The radio IDs are of the form “REM”<2 digit remote number>, where remote number is the number used in

the radio configuration program. For example, if the weather station is located at “Remote 6” and the

repeater is” Remote 11”, then the connect string will be “REM06 via REM11”.

USING REPEATERS WITH NEULINK RADIOS

In order to use the repeater functionality built into the RF Neulink radios, you will have to carefully consider

the design of your radio network and manually configure the radios. This note will explain the important

considerations, but Davis Instruments does not provide support for this feature of the RF Neulink radios.

According to the RF Neulink Operator Manual:

2.4 Store and Forward Repeating

The NEULINK 9600 may be configured to automatically repeat packets of data. This feature is typically used

to fill in areas of coverage where a base station cannot get far enough to talk to a particular unit. It is not

intended as a wide-area networking feature….

Each unit may be programmed with up to four different repeat TOIDs … stored in four REPEAT registers. …

When repeating is enabled the unit will watch the air for packets with a TOID matching any of the four

REPEAT registers. If it sees an ID match…it will automatically transmit the received packet again. …

The Ids that the unit is programmed to repeat may be individual Ids, groups, or all Ids. …

Some important notes concerning the repeater function are; … the automatic ACK feature of the RDXP [Radio

Data Exchange Protocol] protocol will not work in the repeat mode. If ACK is enabled [which it is for the

standard Davis configuration] then the repeat function should not be used.

4.7 Repeater Feature

… [The radio] will retransmit the packet when the carrier is not busy and it is not busy sending its own data.

The unit can only store one packet at a time. The repeater does not check the air for activity before it repeats a

packet. …Do not program two units to repeat the same Ids on the same frequency, as they will tend to transmit

at the same time, causing neither transmission to be heard by others.

These instructions impose the following restrictions on the design of a GroWeather radio network using RF

Neulink repeaters:

• Only one radio can be a repeater radio. This is because one of the Ids the repeater will repeat is the base

radio’s ID because we require 2-way communication. We cannot have two repeaters repeating the same

ID, and thus we cannot have two repeaters.

• The automatic packet acknowledgement feature of the radios must be disabled, which can seriously

degrade the overall performance and reliability of the radio network. Normally, the radios will

acknowledge the receipt of each data packet, or by not acknowledging request retransmission of the

packet. This happens transparently to the weather station and software on either end. Without packet

acknowledgement, only “end-to-end” error checking is available to catch transmission errors. This also

means that “Wireless Ready” (Rev E) WeatherLinks are REQUIRED for networks with repeaters

(instead of being recommended).

• To minimize the amount of extra radio traffic, the repeater ideally would repeat only packets intended for

stations that cannot be reached directly from the base radio. If the REPEAT registers are programmed

with individual radio Ids, then only 3 stations (plus the base radio) can be the recipients of repeated

packets. The radio ID numbers used by the Davis Radio Configuration program (0-32) all fall in the

1 2 3 4

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