Maxiflex T2 CPU User Manual
27
-© Omniflex
UMM124XBR04.pdf
5.3 I/O Slots 1 to 15 DIT Range
These DIT register ranges provide direct access to the I/O Modules installed in the
MAXIFLEX rack.
4000 DIT registers are allocated per slot. Typically, I/O modules will use only a small portion
of this allocated space.
The datasheet for each I/O Module defines the DIT registers allocated on each module.
These registers on the I/O module datasheet will be shown numbered from 0.
To access a DIT register in an I/O module, simply add the DIT register number given in the
I/O module datasheet to the DIT Start Address applicable to its I/O Slot (from the table
above).
DO NOT attempt to read data from the unallocated area of the DIT space, because the
results will be indeterminate.
The access time from these areas of the DIT are slower than from the CPU Dynamic Data
Area (DIT addresses 0 – 3999)
An Example:
If an M1581B Modbus NIM module is present in I/O Slot 1 and a M1431A 8VC ISO
module is present in I/O Slot 2 then access their respective DIT data as follows:
M1581B NIM Module:
To read the Alive Counter of the NIM module, which is DIT register 23 in the DIT
layout of the NIM module, add 4000, which is the DIT Start address for any module in
I/O Slot 1.
Therefore, by reading DIT register 4023 of the T2 CPU, you will read the Alive
Counter of the NIM module fitted in I/O Slot 1.
M1431A 8VC ISO Module:
To set the Input Type of Channel 1 on this VC module, you need to write data to DIT
register 17 of the 8VC module. As the module is in I/O Slot 2, you must add 8000 to
any DIT number you wish to access in this module. This means that by writing to DIT
register 8017 of the T2 CPU, you are in fact writing to register 17 of the 8VC module
fitted in I/O Slot 2.
5.4 CPU Static Data DIT Range:
This DIT area is used to store configuration data for the functions supported in the T2 CPU,
such as Serial Port set up and Network Routing Table information etc.
This Configuration area is stored in non-volatile memory in the CPU, and does not utilise
the internal battery. This means that this data will still be valid even when the on-board
battery is LOW or is being changed.
There is a free area available in this section for the User to store application specific
configuration that will remains fixed for the life of the application.
Writing to this area of the DIT is slower than accessing the Dynamic DIT area, and
continuous writing to this area during normal system operation should be avoided.
