1. Synchronizing Acknowledgements with Group Pokes
The OPC DA protocol provides only for the transfer of raw data values rather than the alarm events. As a result, WIN-911 manages its own instances of alarm conditions and alarm acknowledgments (in addition to any alarm instances that may exist in your SCADA). There are no standardized means of communicating to the SCADA over OPC DA that an alarm has been acknowledged in WIN-911 or vice-versa. In an effort to facilitate just that sort of interaction, WIN-911 has implemented a Group Poke feature. Combined with server-side scripting, alarm states can be synchronized between WIN-911 and your server.
WIN-911 > SCADA
WIN-911 organizes alarms by Group. Each alarm must belong to one and only one Group. As the name implies, the Group Poke occurs on a Group level. The basic idea behind the Group Poke is that when an alarm in a particular Group is acknowledged, a string is written to the HMI server indicating that one of the alarms in that Group has been acknowledged. If you wish to use that information to acknowledge alarms in your HMI, you will need to write a script that listens for that text and acknowledges all alarms that belong to that group. The text GROUP ACKED is used by default.
SCADA > WIN-911
As mentioned previously, the Group Poke is also capable of acknowledging alarms in WIN-911. Whenever WIN-911 reads a string value containing Ack (case-sensitive) from the Group Poke field, WIN-911 will acknowledge all alarms in the group. If you wish to synchronize alarm acknowledgments between your HMI and WIN-911, you will need to write scripts that write the text Ack when an alarm is acknowledged in your server.
It is recommended that the text Ack is written when an acknowledge button is pushed in your server, rather than when an alarm is acknowledged, otherwise it is likely that your server and WIN-911 will continuously write Ack and GROUP ACKED to the same field while repeatedly acknowledging the same set of alarms.
WIN-911 will also use the Group Poke feature to indicate when it detects an alarm by writing the name of the alarm, as well as some other information, to the Group Poke field. The format used is defined on the Format tab of Data Poke definition dialog. This write may interfere with scripts designed to check the field value periodically; where possible, the scripting should consider all changes to the field.
The Group Poke requires you to create a writable string tag on your OPC or DDE server for each alarm group that requires Group Poke functionality. The tag must be configured within WIN-911 as well. Specify the OPC item name or DDE tag in the Group dialog on the Group Poke tab.