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CHAPTER 3

Advanced Functions

• 30 — Error receiving a frame (cyclic redundancy check and

others)

• 31 — An unexpected frame type was received

• 32 — False length (type does not fit its length)

• 35 — Radio timeout when receiving (no answer after a request

• 36 — RF channel in use

Frame Types

The information in this section is intended to programmers writing

their own routines to interface with the A840 Telemetry Gateway.

The A840/A440 combination can communicate with various types

of RTUs. The distinctive frame type of each RTU makes no

difference to the application software on the A840. The software

stores the frame in the memory and retrieves it when needed—

whatever its length is. But it is important for the software on the

host to correctly interpret the frames returned by the gateway.

The data is retrieved from the gateway

using the GETBLOCK command (see

page 71). All frames have certain

common elements: the date/time, the

number of following bytes (including the

frame type), the frame type, and the data

portion. Clearly, the only difference

between the various frames is the data

portion (the size and type are also

different from frame to frame). Following

are descriptions of the frames that are currently in use.

The A730MD frames

The A730MD uses frame type 9.

Type 9

SIZE 21 (including the type byte).

ORMAT struct tlg_type9 {

BYTE RF_LevelIn;

BYTE RF_LevelOut;

BYTE DigiByte;

BYTE PulseCounter0;

date (6 bytes)

time (6 bytes)

size (1 byte)

frame type (1 byte)

data (size bytes)

1 2 ... 87 88 89 90 91 92 93 94 95 96 97 ... 145 146

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Adcon A720 Guía de usuario Pagina 92