Comms Statistics

Associated with: Scanners; Slave sources; most channels on advanced drivers; outstations; Slave outstations

This status attribute displays statistics about the communications with or via a particular item. The information that the attribute displays varies, depending on the type of item with which the attribute is associated.

With a scanner on a simple driver, the statistics that are displayed vary, depending on the type of scanner—see the driver-specific documentation for details.

With a Slave source on a simple driver, the Comms Statistics status attribute displays the number of times that the SCADA master has successfully or unsuccessfully read data from that source.

With a channel on an advanced driver, the Comms Statistics status attribute displays the time period for which the various channel statistics apply. If the Reset Statistics pick action has been used to reset the channel’s statistics, two Comms Statistics entries are displayed—the lower entry lists the time period for which the previous set of statistics applies, the upper entry lists the date and time at which the current statistics commenced.

On a channel on which non-continuous polling is used, the Communication Statistics Updates fields on the Channel Form’s Scan Parameters tab specify when the statistics are updated (see Defining the Communication Statistics Update Rate in the ClearSCADA Guide to Advanced Drivers).

The actual statistics to which the time periods apply are listed below each Comms Statistics entry. Such statistics include a channel’s Message Count.

With an outstation on an advanced driver, the Comms Statistics status attribute displays information about the success, or otherwise, of the communications between the ClearSCADA server and that particular outstation.

The attribute displays the number of:

• Good Messages—A count of the pairs of messages and corresponding replies that have been transmitted successfully between the outstation and ClearSCADA since the statistics were last reset. Each pairing of original transmission and corresponding reply (providing both are successful) count as one good message.
• Unsolicited Messages—Messages that the outstation has sent to the server to inform ClearSCADA of alarms or other data that is awaiting retrieval from the outstation.

Not all outstations support transmission of unsolicited messages.

• Bad Messages—Validly framed messages that either contained unrecognized content (content that was not correct for the request), or that rejected requests such as Control actions.
• No Replies—Messages for which the expected reply was not received within the necessary time period.
• Errors—Any errors reported in response to transmitted messages. For instance, reports of messages being corrupt (typically check sum errors, indicating that a packet has become corrupt during transmission).
• Polls—The number of times that ClearSCADA has polled (scanned) the outstation for data. A poll can comprise one or more messages and is used to collect primary (current) and secondary (logged, time stamped) data. Other actions (such as controls) are not included in this count.

If the Reset Comms Statistics pick action has been used to reset the statistics on an outstation, two Comms Statistics entries are displayed—the lower entry lists the previous communications statistics, the upper entry is ‘live’ and logs the communications statistics since the pick action was last used.

(To ascertain similar statistics for all of the outstations on a particular channel, as opposed to the statistics for a single outstation, look at the channel’s Message Count status attribute.)

With a Slave outstation on an advanced driver, the Comms Statistics status attribute displays information about the success, or otherwise, of the communications between the Slave outstation (ClearSCADA) and its SCADA master.

The attribute displays the number of:

• Good Messages—A count of the pairs of valid messages and corresponding replies that have been transmitted successfully between the Slave outstation (ClearSCADA) and its SCADA master since the statistics were last reset. Each pairing of original transmission and corresponding reply (providing both are successful) count as one good message.
• Unsolicited Messages—Messages transmitted between the Slave outstation (ClearSCADA) and its SCADA master in response to, and including, requests for that data from the SCADA master.

  With a Slave outstation, the Comms Statistics attribute will typically indicate many more unsolicited messages than solicited messages, as each poll from the SCADA master is an unsolicited message. Only messages that the Slave outstation sends to its SCADA master to inform it that the Slave has alarms or other data awaiting retrieval are treated as solicited messages (see Solicited and Unsolicited Data Transmissions).

• Bad Messages—Validly framed messages that either contained unrecognized content (content that was not correct for the request), or that rejected requests such as Control actions.
• No Replies—Messages for which the expected reply was not received within the necessary time period.
• Errors—Any errors reported in response to transmitted messages. For instance, reports of messages being corrupt (typically check sum errors, indicating that a packet has become corrupt during transmission).
• Polls—This count is not used on Slave outstations.

Again, if the Reset Comms Statistics pick action has been used to reset the statistics on a Slave outstation, two Comms Statistics entries are displayed—the lower entry lists the previous communications statistics, the upper entry is ‘live’ and logs the communications statistics since the pick action was last used.