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What is the IO Database in Telepace-based controllers?
The IO database is a large “pool” of memory that exists in the controller and is available for use by logic control applications, TeleBUS protocols and the register assignment table. The IO database consists of four register types:
- Coil registers (1-bit),
- Status registers (1-bit),
- Input registers (16-bit), and
- Holding registers (16-bit).
Until these registers are assigned specific properties by the register assignment table, they are considered general-purpose registers and can be used for internal holding-register purposes.
Each register type has a controller-specific range of valid addresses. The follow diagram illustrates the IO database and the associated register-address ranges for a SCADAPack controller.
The IO database also acts as an interface between the register assignment and the logic programs and TeleBUS protocols. This means, for example, that complex code, written in C/C++, can be triggered by the ladder logic program or by a remote TeleBUS device by writing to the trigger-bit address in the IO database.
