IDEC WindSRV - Manual (Page 66)

65
www.kepware.com
KEPServerEX5 Help
will override the normal polling frequency of tags associated with the device, as well as one-shot Reads and writes. This
delay can be useful when dealing with devices with slow turnaround times and in cases where network load is a
concern. Configuring a delay for a device will, however, affect communications with all other devices on the channel.
Thus, it is recommended that users segregate any device that requires an inter-request delay to a separate channel if
possible. The inter-request delay has a valid range of 0 to 30000 milliseconds. The default is 0, indicating that there will
be no delay between requests with the target device. This setting will be disabled if it is not supported by the driver.
For information on Inter-Request Delay support, refer to the specific driver's help documentation.
Note 1: To determine when communication errors are occurring, use the device's _System Tag, _Error.
Note 2: With the server's online full-time operation, these parameters can be changed at any time. Utilize the User
Manager to restrict access rights to server features in order to prevent operators from changing the parameters.
Device Properties - Auto-Demotion
The Auto-Demotion parameters allow a driver to temporarily place a device off-scan in the event that a device is not
responding. By placing a nonresponsive device offline for a specific time period, the driver can continue to optimize its
communications with other devices on the same channel. After the time period has been reached, the driver will
reattempt to communicate with the nonresponsive device. If the device is responsive, the device will be placed on-scan;
otherwise, it will restart its off-scan time period.
Auto-demotion can be turned on by selecting the Enable auto device demotion on communication failures
checkbox in Device Properties as shown below.
There are three other parameters in the Auto-Demotion tab in Device Properties. Descriptions are as follows.
 Demote after indicates how many successive cycles of request timeouts and retries will occur before the device
is placed off-scan. The valid range is 1 to 30 successive failures. The default is 3 successive failures.
 Demote for indicates how long the device should be placed off-scan when the "Demote after" parameter has
been reached. During this period, no read requests will be sent to the device and all data associated with the
read requests will be set to bad quality. The valid range is 100 to 3600000 milliseconds. The default is 10000
milliseconds. When this period expires, the driver will place the device on-scan and allow for another attempt at
communications.
 Discard write requests during the demotion period is used to control whether or not Write requests should