About this task
Follow the steps in this section to adjust the network sensitivity of the BACnet/IP and MS/TP field bus networks for a network engine. By increasing the number of seconds the network engine waits before flagging a field device as offline, you can minimize the number of false offline reports. Three different sensitivity options, each with a different set of values, are available: high, medium, and low. The default setting for all network engines upgraded to Release 11.0 or later is medium.
- High Sensitivity: Use for critical applications or customer requirements for faster status updates
- Medium Sensitivity (default): Use for a system that does not show any signs of offline cycling
- Low Sensitivity: Use for a system that shows chronic occurrences of offline cycling
- Causes any outgoing confirmed messages to queue up for retries during the time when a remote device stops responding, but has not yet been detected as offline. For supervisory devices that are low on free memory, memory may become exhausted over time, which may cause the supervisory device to restart.
- For an integrated general BACnet device, increases the possibility of missing a device restart. This scenario increases the chances of losing change of value (COV) subscriptions at remote devices for significant periods of time. In addition, commanded values might also be in unwanted states longer than normal.
- For an integrated Johnson Controls-family device, increases the possibility that a slight delay may occur before a device restart is detected, requiring extra time to recover COV subscriptions and commanded values. Detection of the restart event is guaranteed, but old data is present longer than normal.
Do not specify an APDU Timeout or APDU Segment Timeout value that is higher than 30,000 ms, even though the system allows higher values.
Before you begin, verify that the engine is set to run in Expert Mode so that all attributes you need to adjust are available. For details, see Enabling Expert mode. Also, select the Advanced view for all attribute windows.
Follow these steps to adjust the sensitivity values:
Procedure
-
Open the Focus window for the network
engine that you want to adjust. Enter new values for the sensitivity
range that you selected using the values listed in Table 1. Figure 1 shows an
example.
Table 1. Supervisory Device Network Settings Attribute
High Sensitivity
Medium Sensitivity
Low Sensitivity
APDU Segment Timeout
4000 ms
10000 ms
20000 ms
APDU Timeout
6000 ms
10000 ms
20000 ms
APDU Retries
4
4
5
Internode Comm TimerNote: Older FxC controllers have a supervisory status module that times out unless the Internode Comm Timer is set to high sensitivity.20 seconds
120 seconds
240 seconds
Figure 1. Example: Supervisory Device Network Settings
-
Open the Snapshot Focus window for the BACnet Protocol Eng integration of the network engine that you want to
adjust. Enter the Poll Delay for the sensitivity range that you selected using
the value listed in Table 2. Figure 2 shows an
example.
Table 2. BACnet Protocol Eng Network Settings Attribute
High Sensitivity
Medium Sensitivity
Low Sensitivity
Poll Delay
20 seconds
60 seconds
120 seconds
Figure 2. Example: BACnet Protocol Eng Network Settings
-
Open the Snapshot Focus window for the BACnet IP integration of the network engine that you want to adjust.
Enter new values for the sensitivity range that you selected using the values
listed in Table 3. Figure 3 shows an
example.
Table 3. BACnet IP Network Settings Attribute
High Sensitivity
Medium Sensitivity
Low Sensitivity
APDU Segment Timeout
8000 ms
11000 ms
20000 ms
APDU Timeout
6000 ms
12000 ms
20000 ms
APDU Retries
3
4
5
Internode Comm Timer
30 seconds
120 seconds
240 seconds
Figure 3. Example: BACnet IP Network Settings
-
Open the Snapshot Focus window for the integration of the network engine that you want to
adjust. Enter new values for the sensitivity range that you selected using the
values listed in Table 4. Figure 4
shows an example.
Table 4. Field Bus MS/TP Network Settings Attribute
High Sensitivity
Medium Sensitivity
Low Sensitivity
APDU Segment Timeout
6000 ms
12000 ms
30000 ms
APDU Timeout
8000 ms
11000 ms
29000 ms
APDU Retries
3
3
5
Internode Comm Timer
30 seconds
120 seconds
240 seconds
Figure 4. Example: Field Bus MSTP Network Settings