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Serial communication, SPA
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When communicating remotely with a PC using the rear SPA port, the same hardware
is needed plus telephone modems.
The software needed in the PC, either local or remote, is CAP 540.
When communicating to a front-connected PC, the only hardware required is the spe-
cial front-connection cable.
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The parameters for the SPA communication are set via the local HMI. Refer to the
Technical reference manual for setting parameters and path in local HMI.
The SPA and the IEC use the same rear communication port. To define the protocol to
be used, a setting is done on the local HMI. Refer to the Installation and commissioning
manual for setting procedure.
When the type of communication protocol is defined, the power to the terminal has to
be switched off and on.
The most important settings in the terminal for SPA communication are the slave num-
ber and baud rate (communication speed). These settings are absolutely essential for all
communication contact to the terminal.
These settings can only be done on the local HMI for rear channel communication and
for front channel communication.
The slave number can be set to any value from 1 to 899, as long as the slave number is
unique within the used SPA loop.
The baud rate, which is the communication speed, can be set to between 300 and 38400
baud. The baud rate should be the same for the whole station, although different baud
rates in a loop are possible. If different baud rates in the same fibre optical loop are used,
consider this when making the communication setup in the communication master, the
PC. The maximum baud rate of the front connection is limited to 9600 baud.
For local communication, 19200 or 38400 baud is the normal setting. If telephone com-
munication is used, the communication speed depends on the quality of the connection
and on the type of modem used. But remember that the terminal does not adapt its speed
to the actual communication conditions, because the speed is set on the HMI of the ter-
minal.
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