65
PROFIBUS-DP Master DTM
Section 3-3
The table below lists the Bus Parameters, which are shown in the Bus Param-
eter tab.
Item Description Unit Editable
by User
Baud rate Defines the transmission rate on the PROFIBUS-DP Network. The following baud
rate values are defined by the PROFIBUS-DP standard:
• 9.6 kBits/s
• 19.2 kBits/s
• 45.45 kBits/s
• 93.75 kBits/s
• 187.5 kBits/s
• 500 kBits/s
• 1500 kBits/s
• 3000 kBits/s
• 6000 kBits/s
• 12000 kBits/s
The default value is 1500 kBits/s.
-- Yes
Optimize The Optimize setting defines whether or not selected parameters can be changed
by the user.
• By Standard
Forces the user to use the default (optimized) settings.
•By User
Makes selected fields editable.
Note 1. If the By User option is selected and changes have been made, it is
still possible to switch between Optimize settings, without the changes
being lost.
2. If the By User option is selected and the baud rate is changed, the pa-
rameters will be optimized to the new baud rate.
-- Yes
Slot Time The maximum time a Master Unit must wait for a response to a request message. t
BIT
Ye s
Min. Station Delay
of Responders
The minimum allowed time for a slave station before it will generate a response to
a request message.
t
BIT
Ye s
Max. Station Delay
of Responders
The maximum allowed time for a slave station to generate a response to a
request message.
t
BIT
Ye s
Quiet Time The time a transmitting station must wait after the end of a message frame,
before enabling its receiver.
t
BIT
No
Setup Time The time between an event and the necessary reaction. t
BIT
No
Min. Slave Interval The Minimum Slave Interval defines the poll cycle, i.e. the minimum time between
two consecutive Data_Exchange Cycles to the same slave station. The Minimum
Slave Interval must be smaller than the Target Rotation Time.
t
BIT
Ye s
Calculated Minimum Slave Interval in milliseconds. ms No
Target Rotation
Time
The anticipated time for one token cycle, including allowances for high and low
priority transactions, errors and GAP maintenance. Do not change the value
below the calculated value, to avoid bus communication interruptions.
t
BIT
Ye s
Max Retry Limit Maximum number of request transmission retries by this master if a station does
not reply to a request.
-- Yes
Highest Station
Address
The HSA defines the Highest Master station address on the network, of which the
Master station will request the FDL status, when updating the active station list
(See GAP Update Factor).
Shows the station address of the master. If new slaves are added to the network,
this field shows the highest station address.The Master will periodically check
whether new active stations have been added between address its own address
and the Highest Station Address. If any stations are detected, GAP is updated.
Permissible values are in the range of 2 to 126.
-- Yes
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