The type of read / write to preform. Note that not all types can be written. For example an attempt to write to D_INPUTS or INPUTREG would cause an EINVAL error. Also you can not directly write to SETUPREGS, you must use an appropriate Ioctl.
| Enumerator |
|---|
| COILS | Coils are any relay type outputs.
|
| D_INPUTS | Digital inputs. Single bit inputs.
|
| HOLDINGREG | Configuration registers.
|
| INPUTREG | Registers only used on A/D type devices.
|
| SETUPREG | Advanced device configuration registers.
|
| SEAMAXPIO | Programmable type I/O.
|