Bus parameters
Setting
range (de‐
fault)
Meaning and limiting values
Maximum Scheduling
Overhead
16
This parameter extends the time that may be used by the LAS for processing the
schedule. The parameters unit is the transmission duration of one octet.
The following times should be included in the duration:
● The time allocated for each scheduled activity
● The time to determine whether a device on the FF segment can serve as an LAS.
● The time for the organization of the schedule.
The parameter will be checked based on the value configured in the LAS during
downloading of the FF segment.
The minimum value for this parameter is determined by the maximum value of all
the LAS-capable devices in the FF segment.
Max Inter Chan Signal
Skew
0 - 7
(0)
This parameter indicates the maximum permitted time offset of the data that a device
receives from several ports (redundant routes) via an H1 connection.
Select a value between 0 and 7 4-bit transmission times.
The value range is (0 .. 7) * 4 * Tb.
Post Trans Gap Exten‐
sion
0 - 7
(0)
There will be an interruption of the signal transmission in 4-bit transmission times
after each transmission.
Use this parameter to increase this interruption in signal transmission by additional
4-bit transmission times. The value range is (0 .. 7) * 4 * Tb.
A value greater than 0 increases PerDlpduPhlOverhead.
Default Minimum To‐
ken Delegation Time
32 - 32767
(86)
The time required for an FF device to process all tasks. The parameters unit is the
transmission duration of one octet.
Keeping to the schedule (controlled by LAS ) has the highest priority on the FF. The
time available for an FF device should be sufficiently dimensioned (greater than
Default Token Holding Time).
An FF device can only be processed if it keeps the token for longer than stipulated
by the "Default Minimum Token Delegation Time" parameter.
Default Token Holding
Time
276 - 65000
(276)
Time period assigned to an FF device by the LAS for the following tasks:
● acyclic bus traffic
● System Management
● Alarms and events
Target Token Rotation
Time
1 - 60000
(60000)
Within this time all FF devices must have received the token for acyclic data transfer
once. If the actual token rotation time is higher than the configured value for Target
Token Rotation Time, the LAS will increase the token priority.
A Target Token Rotation Time value that is too small causes the failure of low-priority
services. The following are low-priority services:
● System Management
● acyclic bus traffic (client-server connections)
Link Maintenance To‐
ken Holding Time
292 - 65000
(336)
Period of time which the LAS uses within a token rotation for checking a link. This
time period contains the following processes:
● find new FF devices
● send LAS status telegrams
Time Distribution Peri‐
od
10 - 55000
(5000)
Time period for forwarding time service telegrams (in milliseconds)
Time distribution PDU's will be sent on the bus in 95% or less of that time period.
Engineering
5.3 Parameter assignment
FOUNDATION Fieldbus
46
Commissioning Manual, 02/2015, A5E32711026-AC
