3.4 Special signals
Additional diagnostic signals are available, namely:
ErrorFrame | number of invalid frames received |
ErrorTimeout | number of timeout occurences |
ErrorData | number of valid frames with unexpected data or error code |
ErrorReset | flag for resetting the above mentioned counters |
Browse | non-zero value switch driver into browsing address space mode. Output is in system log. |
Every signal also has its attributes, namely:
_Value | alias for signal value |
_ReadEnable | configuration parameter Readable |
_WriteEnable | configuration parameter Writable |
_Address | configuration parameter Item address |
_Slave | configuration parameter Slave address |
_Fresh | time elapsed since the last data update (in seconds) |
_Period | configuration parameter Refresh rate |
_Send | flag indicating that the value is waiting to be stored in the Slave device |
The Fresh attribute is read-only, the other attributes are both readable and writable. Beware the Fresh attribute is updated even if the read/write operation fails. In such a case the signal quality is set to BAD or UNCERTAIN.
Thus if we want to know the freshness of the MBM__IN signal, we use the From block and set the Goto Tag parameter to MBM__IN_Fresh.
There is also one more signal representing the state of the Slave device. E.g. the MTM__SlaveStation signal tells us if the SlaveStation device is operational. To determine whether the Master is trying to establish connection with the slave device, use the MTM__SlaveStation_Connecting signal (it remains on even after the Slave station starts responding). Once the connection is established the MTM__SlaveStation_Connected signal is on.
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