Step 3. Configure Port General Properties

General properties for a new port are as follows.

A Description
B Scan rate
C Retry count
D Enable
E Enable stale data
Note: Tab2 in the graphic above represents the port-specific tab, whose name depends on what port is being configured.
A Description

A description can be up to 40 characters of explanatory text about the port.

B Scan rate

The basic timer for points monitored from this port.

The rate at which points are polled is a multiple of this Scan Rate.

Configurable units can be set in any of the following units.

  • Ticks (hundredths of seconds)
  • Seconds
  • Minutes
  • Hours
C Retry Count

Specifies the number of times to retry communications to devices on this port after a communications error is encountered

If communications cannot be established, devices on this port are considered to be down, and a $DEVICE_DOWN alarm is generated for each device.

Once a device is down, periodic attempts are made to resume communications to the device.

D Enable

Do one of the following.

Check Enable communications on this port.
Clear Disable communications on this port.
guide: When a port is dynamically disabled, communication to all devices associated to that port will stop.

By default, when the port is dynamically disabled:

  • The associated devices will be marked Down and their associated points will be marked Unavailable.
  • Setpoints and processing of unsolicited data will not be allowed for the associated devices.
Tip: As an alternative to this default action, you may configure a Global Parameter, ALLOW_UPDATE_WHEN_DISABLED, to keep the associated devices alive.

If ALLOW_UPDATE_WHEN_DISABLED is configured, then when the port is dynamically disabled:

  • The device is not marked Down.
  • Polling stops.
  • Setpoints and unsolicited messages will still be processed.
E Enable Stale Data

Check Enable stale data to keep the point available in most circumstances that would have made it unavailable. However the point value will be stale, meaning it is the last known value and may or may not have changed in the device.

The following table displays a point's availability when events occur and QUALITY.STALE_DATA is configured as on or off.

Point Availability when Stale Data is Configured
Event On Off
Poll Failure Available Unavailable
Process Shutdown Available Unavailable
System Shutdown Not Applicable Unavailable
Ind. Point Unavailable Available Unavailable
Out of PTMRP Range Limits Range Bit / Available Unavailable
DC Sends Device State Available Unavailable
DynCfg Disable Point/Device Unavailable
Tip: Use QUALITY.STALE_DATA (Attribute) to report if the point value is stale.