Device registers

Item references are addresses of device registers, and device registers are specific locations in a device's memory.

In most cases, each item reference has the following attributes:

register type

What the memory location is used for. Register types include inputs, outputs, link relays, latch relays, timer bits, and so on. For limitations on register types, see the manufacturer's documentation for your device.

range

The range of valid addresses for a given register type. A complete address typically consists of a prefix indicating the register type and a numerical value indicating the specific memory location.

data type

The types of data the client can request when it accesses the specified memory location. Data types include Short, Word, BCD, and so on. The data type is often optional because most memory locations have a default data type.

access

What a client application can do with the memory location. Some locations are read only or write only, while others are fully read/write.

For a complete description of the item reference syntax and options, see the Communication Driver-specific documentation.