22.6.17
UNIGATE
®
fieldbus gateway UNIGATE
®
EL - DeviceNet
™
V. 1.0
22
Deutschmann Automation GmbH & Co. KG
Generating a Script
In the following please find a listing of baud rates at a 40 MHz-crystal frequency with the corre-
sponding errors:
4800 baud: 0.16%
9600 baud:
0.16%
19200 baud:
0.16%
38400 baud:
1.35%
57600 baud:
1.35%
62500 baud:
0%
115200 baud:
1.35%
312500 baud:
0%
625000 baud:
0%
8.8 Script processing times
The Script is translated by the PROTOCOL DEVELOPER and the consequently generated code
is loaded into the Gateway. Now the processor in the Gateway interprets this code. In this case,
there are commands that can be processed very fast (e. g. "
Set Parameter
"). There are also
commands, however, that take longer (e. g. copying 1000 bytes). Consequently, for one thing the
processing time differs due to the kind of Sript command. But the processing time of the Script
commands is considerably more determined by the processor time that is available for this pro-
cess. Since the processor has to carry out several tasks simultaneously (multitasking system)
only a part of the processor's capacity is available for the Script processing. The following tasks -
in the order of priority - are executed on the processor:
•
Sending and receiving data at the Debug-interface (provided that the PROTOCOL
DEVELOPER has been started on the PC)
•
Sending and receiving data at the RS-interface
•
Sending and receiving data at the Fieldbus-interface
•
Tasks controlled via internal clock (1 ms) (e. g. flashing of an LED)
•
Processing of the Script
From experience approximately 0.5 ms can be calculated for each Script line. This value confir-
med itself again and again in many projects as a standard value. He is always quite right if the
processor has enough time available for the Script processing.
By means of the tasks mentioned above, the following recommendation can be formulated in
order to receive a rather fast Script processing:
•
Deactivate the Debug-interface (it is the normal case in the serial use)
•
Keep the data length at the RS-interface as small as possible. The baud rate is not the problem
here, but the amount of characters which are transfered per second.
•
Do not unnecessarily extend the data length at the Fieldbus side. Especially at acyclical bus
data, if possible do only send them when changes were made. The data length at buses that
are configured to a fixed length (e. g. PROFIBUS) should not be longer than absolutely neces-
sary.
If the processing time should be too large in spite of these measures, there is the possibility to
generate a customized Script command, that executes several tasks in one Script command.
Please contact our support department for this purpose.
