In addition to the usual data fields that you would expect to find on a Geo SCADA Expert Channel, a ROC Plus Channel object also has the following data fields, which are listed in the Geo SCADA Expert Database Schema (see Schema View). The name in bold at the start of each entry is the OPC tag name.
- CommBadResponses. This is the number of times that a message with a bad CRC is received by the channel. This counter is reset when the ResetCommCounters method is executed.
- CommBadTcpConnTries. This is the number of failed connection attempts to the ROC. The Geo SCADA Expert ROC Plus Driver will hold a TCP/IP connection open for a user configurable time. If this time passes with no activity on the connection, the connection is closed. On the next scan, or refresh, or control request, a new connection attempt is made. Failed connection attempts cause this counter to increment. This counter is reset when the ResetCommCounters method is executed. This field does not apply if the ROC Plus Channel is configured to use a serial connection.
- CommCountersTime. This field indicates the time that the counters for the ROC Plus Channel object were reset.
- CommGoodResponses. This is the number of good responses from the ROC. This counter is reset when the ResetCommCounters method is executed.
- CommTcpConnTries. This is the number of TCP/IP connection attempts to the ROC, whether they are successful or not. The Geo SCADA Expert ROC Plus Driver opens a new TCP/IP connection at the start of a scan and closes the connection at the end of the scan. This counter is reset when the ResetCommCounters method is executed. This field is unused if the ROC Plus Channel is configured to use a serial connection.
- CommWriteCount. This counter increments every time a ROC Protocol packet is transmitted to the ROC. This counter is reset when the ResetCommCounters method is executed.
- TcpConnected. This tag is TRUE if the TCP/IP socket in the driver is actively connected to the endpoint, and FALSE if it is disconnected. This tag enables you to check that the TcpConnectionTimeout setting is working as expected.
The TcpConnected tag might not reflect the fact that the connection was closed by the endpoint, or by some device in the communications chain. The only way to test if a socket is actually connected is to transmit some bytes, but this takes time. In the interest of efficiency, the connection to the endpoint is not continuously tested. The TcpConnected tag reflects the state that the driver thinks that the socket is in, and is set to TRUE when the socket is opened by the driver and set to FALSE when the socket is closed by the driver.