An object of the I/O tag type may acquire values, which are described in the following tables for individual types (only the types, listed below, are described in the tables).
Object value | Cause |
---|---|
D_False | *FALSE value |
D_True | *TRUE value |
D_Oscillate | Oscillating value (TRUE <-> FALSE). The system sets a value as oscillating according to defined parameters of filtering - Oscillation limits |
*Valid for the normal polarity. In case of the inverse polarity, then opposite values are valid.
Object value | Cause |
---|---|
D_False | *FALSE value |
D_True | *TRUE value |
D_Oscillate | Oscillating value (TRUE <-> FALSE). The system sets a value as oscillating according to defined parameters of filtering - Oscillation limits |
*Valid for the normal polarity. In case of the inverse polarity, then opposite values are valid.
Quaternary inputs are used e.g. in power engineering. Example of use: opening a valve with logical sensors of the end positions closed and open - can be in the following states:
Object value | Cause |
---|---|
Q_Off | OFF value |
Q_On | ON value |
Q_Trans | TRANS value (transition from ON to OFF or vice versa is in progress) |
Q_Err | ERR value (error state) |
Q_Oscillate | Oscillating value (On <-> Off). The system sets a value as oscillating according to defined parameters of filtering - Oscillation limits. |
If no control object and no default value are defined for an I/O tag, its value will be invalid after starting the D2000 system.
After the D2000 KOM process is (re)started, it internally invalidates the values of all I/O tags. This could be undesirable behaviour (e.g. the values of output I/O tags in server protocols), therefore starting process D2000 KOM with the parameter /KI allows to enable reading the initial values of I/O tags (input as well as output ones) from the D2000 Server process after starting the D2000 KOM process.