149
Bus Parameters
Appendix A
A-3
Determining the Bus Parameters
The bus parameters defined in the previous paragraph are used to configure the PROFIBUS-DP hardware
interface and to calculate the cycle time for I/O data exchange as well as the watchdog value. Most of the
parameters, set in the Bus Parameter Tab are directly transferred to the interface hardware registers. The table
below, lists these parameters, along with their default value for the available baud rates
Highest Station Address
HSA
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
GAP Update Factor
G
The GAP update factor defines the amount of updates of
the active stations (i.e. Master stations) list times during
one token rotation cycle.
To update the list, the Master station will transmit
FDL_Status_request messages to ascending station
addresses until it finds a next Master station, or until it
reaches the Highest Station Address (See HSA below).
The GAP Update Factor is fixed to 1.
--
No
Poll Timeout
--
The maximum time interval that this master station may
need for the execution of a master-master function.
ms
No
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 = 7*T
WD
.
ms
No
Watchdog Control
T
WD
The Watchdog Control Time defines the time for a slave
station to set its outputs to a fail-safe state, if during that
time no communication between the Master station and
that slave station was detected. The Watchdog is
automatically set for all configured slaves, based on the
value of T
TR
.
ms
Yes
Baud rate
T
QUI
T
SET
T
SL
G
Retry Limit
Poll
Timeout
min T
SDR
max T
SDR
[t
BIT
]
[t
BIT
]
[t
BIT
]
[ms]
[t
BIT
]
[t
BIT
]
9.6
0
1
100
1
1
10
11
60
19.2
0
1
100
1
1
10
11
60
45.45
0
95
640
1
1
10
11
400
93.75
0
1
100
1
1
10
11
60
187.5
0
1
100
1
1
10
11
60
500
0
1
200
1
1
10
11
100
1500
0
1
300
1
1
10
11
150
3000
3
4
400
1
2
10
11
250
6000
6
8
600
1
3
10
11
450
12000
9
43
1000
1
4
10
11
1600
Item
Symbol
Description
Unit
Editable
by User
Summary of Contents for SYSMAC CJ1W-PRM21
Page 2: ...iv...
Page 36: ...22 Basic Operating Procedure Section 1 5...
Page 52: ...38 Defining PROFIBUS DP in the Software Section 2 5...
Page 112: ...98 Allocated CIO Area Words Section 4 2...
Page 122: ...108 Command Response Reference Section 5 2...
Page 160: ...146 Replacing the Unit Section 7 8...
Page 174: ...160 Appendix...
Page 180: ...166 I O Data Conversions Appendix D...
Page 186: ...172 Configurator Error and Warning Messages Appendix E...
Page 187: ...173 Index...
Page 188: ...174 Index...
Page 190: ...176 Revision History...