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C200HW-PRM21 PROFIBUS Master DTM
Section 2-4
Adjusting Bus Parameters
I
f the bus configuration is changed and these changes have effects on the
Bus Parameters, a note symbol
appears next to the concerned parame-
ters of which displayed values are not longer valid. Usually in these cases the
displayed values are too small and will eventually lead to communication
problems.
The marked parameters need to be recalculated, which can be accomplished
by pressing the Adjust button at the bottom right of the Bus Parameter tab.
After re-calculation the note symbol will disappear.
Note
In case of large networks, it may be required to increase the Watchdog time to
allow the network to become fully operational.
Address Table Tab
The Address Table tab displays the mapping of the I/O data from/to the allo-
cated slave devices on to the internal I/O memory of the Unit. The mapping
can be made automatically, but can also be changed by the user, before
downloading.
The Address Table tab is shown below, containing example data.
Highest Station
Address
The HSA defines the Highest Station Address of Master devices on the network,
of which the Master device will request the FDL status, when updating the active
device list (See GAP Update Factor).
If new slaves are added to the network, this field shows the highest device
address.The Master will periodically check whether new active devices have
been added between its own address and the Highest Station Address.
Permissible values are in the range of 0 to 126.
--
Yes
Data Control Time
The cycle time in which the master updates its Data Transfer List, in which it
keeps an overview of all slave states. Data Control Time is based on the
Watchdog time T
WD
: Data Control Time = 6*T
WD
.
ms
Yes
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 device. The Minimum
Slave Interval must be smaller than the Target Rotation Time.
µ
s
Yes
Watchdog Control
Override slave specific Watchdog control time.
This setting - when selected - allows the user to set one Watchdog Control Time
for the whole network and override the Watchdog Control Time provided by the
Slave DTM.
--
Yes
The Watchdog Control Time defines the time for a slave device to set its outputs
to a fail-safe state, if during that time no communication between the Master
device and that slave device was detected. The Watchdog is automatically set for
all configured slaves, based on the value of T
TR
.
ms
Calculated Timing
The Calculated Timing is the time that the Sender spends at idle after the receipt
of the last Bit of a telegram on the Bus, until the first Bit of a new telegram is sent
on the Bus.
These values are calculated by the DTM and only displayed for information
purposes.
t
BIT
No
Auto-Clear ON
When selected, the Unit transitions to the CLEAR mode in the event of a network
error, e.g. because one or more configured slaves are not in the Data Exchange
mode.
--
Yes
Item
Description
Unit
Editable
by User
!