Horner APG SmartStack I/O HE800PBS600/HEPBS600 - Manual (Page 34)

Setings
MAN0575-04-EN
PAGE 34 of 97
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Profibus Modules User Manual
EO 09-0009
Note: The offline Bus Parameters are displayed. The Bus Parameters are only accepted by the device upon
download of the configuration.
The Baud rate must be set to be the same for all devices on the bus. The result of changing the Baud rate is
that all other parameters must be re-calculated. The System Configurator tests whether the Baud rate is
supported by all configured PROFIBUS-DP Slave devices based on entries in the GSD files. If the System
Configurator recognizes at least one device that does not support the selected Baud rate, then an error
message will appear.
The highest station address is the highest bus address up to which a Master searches for another Master
on the bus in order to pass on the Token. This station address must on no account be smaller than the
Master station address.
For PROFIBUS-DP, the field Access monitoring time is used for the entry of the monitoring time of the
Slave. If the time chosen for this is too short for a low Baud rate, then it is possible that the Slaves will set
their outlets to zero. If the time chosen is too long, it is possible that if an interruption occurs, the Slaves will
take a long time to set their outlets to zero.
For PROFIBUS-DP, the Auto Clear setting is provided for global error handling. The DP Master monitors the
user data exchange (Data Exchange) to all DP Slaves by means of a timer. If no data exchange occurs to at
least one DP Slave, or an existing data exchange takes place after the expiration of a monitoring time, and the
Auto clear mode option is ON, then the Master leaves the Data Exchange and sets the outlets of all
assigned DP Slaves into a secure condition.
5.4
Description of the Individual Parameters
All times for the Bus, parameters are given in Bit times.
The Bit time t
Bit
is the result of the reciprocal of the Baud rate:
t
Bit
= 1 / Baud rate (Baud rate in Bit/s)
Formula 1: Bit time t
Bit
The conversion from milliseconds into a Bit time is shown in the following formula:
Bit time = Time [milliseconds] * Baud rate,
Formula 2: Conversion into Bit time t
Bit
The Bus parameters and their meanings:
Baud rate
Transfer speed: number of Bits per second.
Baud rate Bit time (t
Bit
) Max cable length (type
A)
9,6 kBaud 104,2 us 1200 m
19,2 kBaud 52,1 us 1200 m
93,75 kBaud 10,7 us 1200 m
187,5 kBaud 5,3 us 1000 m
500 kBaud 2 us 400 m
1,5 Mbaud 666,7 ns 200 m
3 Mbaud 333,3 ns 100 m
6 Mbaud 166,7 ns 100 m
12 Mbaud 83,3 ns 100 m
Table 8: Baud rates, Bit times and cable lengths
Note: The maximum cable length is dependent on the Baud rate.