User manual

IEC61131 User and Reference Manual
April 22, 2008
380
Duplex
The TeleBUS protocols communicate in one direction at a time. However the type of serial
data link used determines the duplex setting. The table below shows the possible settings for
SCADAPack and TeleSAFE controllers. Note that not all port types are available on all
controllers.
Port Type
Possible Settings
Recommended Setting
RS-232 or
RS-232
Dial-up
modem
half duplex
full duplex
Use full duplex wherever
possible.
Use half duplex for most
external modems.
RS-485
half duplex
full duplex
Slave stations always use half
duplex.
Master stations can use full
duplex only on 4 wire systems.
Protocol Parameters
The TeleBUS protocols operate independently on each serial port. Each port may set the
protocol type, station number, protocol task priority and store-and-forward messaging
options.
The port configuration can be set in four ways:
 using the TelePACE or ISaGRAF programs;
 using the set_protocol function from a C or C++ application program;
 writing to the I/O database from a C, C++, ISaGRAF or ladder logic application program;
 writing to the I/O database remotely from a Modbus compatible device.
To configure protocol settings through the I/O database, add the module, CNFG Protocol
settings, to the Register Assignment for TelePACE applications or use the setprot function in
ISaGRAF applications.