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3. GDNet Protocols
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Auto-configuration. The network auto-configures at reset (within less than 100
msec with 7 slave devices). Configuration messages are sent along with the typi-
cal cycle messages.
3.1. GDNet communication states
The GDNet master device behaves differently depending on its state.
Possible states are listed in the table below. Note that the HardReset state is not
part of the communication as it is not enabled. Net_ID is the network identifier
(1..3), Slave_num is the slave device identifier (1..7) and CONFIG01 refers to the
main data area (for further details, see Database and Alias).
GDNet is a protocol with a cyclical, isochronous architecture based on
switched Ethernet 100BaseT, used to exchange process data with I/O and
motion devices.
It enables connection between one master and N slave devices
Communication is via star connection topology (Switched Ethernet) backed
by standard "store&forward" switching.
Once the Length/Type field equal to 0xFFAE has been identified, the protocol
supports 3 sequential network scans (Nr=1..3)
Network1 -> Network2 -> Network3 -> Network1 -> Network2 -> ....
Each network supports the continuous scanning of Ns slave devices
(Ns=1..7), where a slave device is defined as a typical message (comprising
48 input words and 48 output words, of which 16+16 usable by the EXP-ETH-
GD-ADV) supplemented with sporadic access data structures (255 contigu-
ous data structures each composed of a maximum of 64 words).
Nome
Net_ID
stato
HardRESET
1
SoftRESET
1
PROG
Net_ID
OPERATE
Net_ID
FAIL
Net_ID
Slave_ID
Risposta a richiesta
database
0
Non esiste comunicazione
0
Messaggio di ALIAS
CONFIG01
Slave_ID
Database di INPUT corrente
Slave_ID
Database INPUT corrente
Slave_ID
Database INPUT (ultimo
valido)
Uscite slave
Come da reset hardware
Come da reset hardware
Congelate
Database OUT corrente
Come da reset hardware
EN- 19
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