Purpose
The Digital Output (DO) block sends a digital value (1 or 0) to an I/O driver or OPC server every time it receives a value from an upstream block, an operator, a Program block, a script, or from its Initial Value field.
Because iFIX processes Digital Output blocks whenever a new value is sent to the hardware, they generally operate as though they were latched. If you configure a Digital Output block as a stand alone block, it outputs a digital value each time the value changes.
Features
The Digital Output block:
- Is a primary block.
- Can be used as a stand-alone block.
- Can be used in a chain with exception-based or time-based processing.
- Can read back the current PLC value when iFIX starts or when the database is reloaded. Values are only read back when the database is initialized.
- Can receive values from a Program block or a script.
- Can be configured using the "Write if Different" output option to prevent a write by the DO block if the value in the driver is the same as the value that is to be written. The DO block will read the bit from the driver and if different, execute the write. If the values are the same, no value is written on this scan.
