I/O Scanner: Device Control Block

Device Control Block

The device control block is a block of 4 word () topological objects that enable and disable the I/O scanner for each table entry.

Each device control block bit corresponds to an entry in the I/O Scanner table. Each entry represents one logical device:

To disable an individual scanner device:

Step	Action
1	Create element variables with predefined IODDT type T_COM_ETH_BMX.
2	Set the bit to 1 to disable it from within the application or from an animation table.

WARNING

UNEXPECTED EQUIPMENT BEHAVIOR

Do not create I/O Scanner entries with both read and write lengths set to0.

Failure to follow these instructions can result in death, serious injury, or equipment damage.

NOTE: A value of 1 in the device control block bit disables the I/O Scanner table entry. A value of 0 in the device control block bit enables the entry. Each entry corresponds to a particular logical device in the IO Scanning configuration table.

Each I/O Scanner table entry can be disabled by setting the corresponding device control bit to 1. The following table shows the mapping between the I/O Scanner table entries and the device control bits stored in %QW topological objects:

Table Entry	Device Control Bits	Comment
1	%QWr.m.c.0.0	r: rack number m: slot number located by the module c: module channel number (always 0 for the BMX NOE 01x0) The device control block bits are mapped to I/O Scanner entries (%QWrack.slot.channel.word(0-3). Example: Table entry 2 can be disabled by setting %QWr.m.0.0.1 to 1. (%QWr.m.0.0.1 is associated with DISABLE_IO_2 in the predefined IODDT type T_COM_ETH_BMX for the BMX NOE 01x0 modules.)
2	%QWr.m.c.0.1
3	%QWr.m.c.0.2
. . .
17	%QWr.m.c.1.0
18	%QWr.m.c.1.1
19	%QWr.m.c.1.2
. . .
33	%QWr.m.c.2.0
34	%QWr.m.c.2.1
35	%QWr.m.c.2.2
. . .
49	%QWr.m.c.3.0
50	%QWr.m.c.3.1
51	%QWr.m.c.3.2
. . .
64	%QWr.m.c.3.15

NOTE: M340 devices use topological addresses to represent device control block bits. Premium and Quantum PLCs have data structures that differ from this.