3.3 Special signals

In some cases, it is useful/necessary to access the status or configuration variables of the driver. The signals below marked with the R (W) letter are readable (writeable) signals, i.e. they are inputs (outputs) of the control system.

The driver performs these special signals:

_DGNRESET W

reset of the accumulated diagnostics information

_TRANSACTIONS R

total number of transactions with owserver

_RECONNECTS R

number of reconnections (after communication errors)

All global signals starts with the _ (underscore) character. In these cases the tripple underscore will be used (e.g. OWS___DGNRESET) because of the __ (double underscore) separator between the diver tag and the signal name.

Moreover, each signal can be suffixed with a special text which determines that a special attribute of the signal will be used instead of the signal value. The special suffixes are the following (all begins with _):

_Value RW

alias for signal value

_DGNRESET W

reset of the diagnostics information for the given signal

_TRANSACTIONS R

number of transactions with owserver for the given signal

_ReadEnable RW

enable to read the signal; equivalent: _RE

_WriteEnable RW

enable to write the signal; equivalent: _WE

_WriteOneShot W

one-shot write of the signal; equivalent: _WOS

_Alarm R

alarm flag of the signal; after reading it is cleared

_PerFactor R

driver period multiplier for the signal update

_PerCount R

number of the driver periods from the last signal update

_PerMax R

maximum number of the driver periods between two consecutive signal updates

_PendCount R

current number of waiting cycles for returning the value from owserver

_PendLast R

last number of waiting cycles for returning the value from owserver

_PendMax R

maximum number of waiting cycles for returning the value from owserver

_Period R

update period (in seconds) of the signal

_Age R

the time elapsed since the last update of the signal (signal age)

_AgeMax R

maximum signal age from the last reset of the diagnostics information