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.