405.1200.037.2 - Rel.: 2.21 of 25/02/2008
35-15
The maximum number of public objects is 128, making a total of
1024 Bytes.
The client terminal is the one that uses the public variables made available
by the server terminal. The terminal that uses public variables and, in its
turn, makes others available is known as the server/client. Generally, the
client terminal has no device of any kind connected.
The example in the figure shows eight terminals connected, of which:
1 -> Server/Client -> V/VP -> Device
2 -> Server/Client -> V/VP -> Device
3 -> Server/Client -> V/VP -> Device
4 -> Client -> V
5 -> Server -> VP -> Device
6 -> Server/Client -> V/VP -> Device
7 -> Client -> V
8 -> Client -> V
The area colored green (VP) represents the public variables, the area col-
ored yellow (V) represents the variables; the device is indicated schemati-
cally in violet (D). The two central rings, one represented by a continuous
red line indicates the VT’s response to a request (the dotted lined traced in
blue indicates the request for information.
A network can have more than one server, more than one client and more
than one server/clients, the total being 32 terminals.
The network participants must each have a different address; the address of
the terminal is configured using the VTWIN (see Software Manual).
A terminal can connected to the network either using the communication
standard RS485 and the MSP and ASP (default) serial ports or, alterna-
tively, using an RS485 serial module (optional) - (see
“Chapter 34 -> Video
terminal accessories“).
To avoid any problems, the device to be connected to the VT must
be connected using the MSP port; the ESA-NET network must
therefore be connected over the ASP port or the field network. If the
VT is to be connected only to the ESA-NET network, the MSP can also
be used.
The VT can operate at a speed of from 38400 to 187500Baud; all partici-
pants in the network must be set to the same transmission speed.
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