Rockwell Automation SB3000 Configuration and Programming - Manual (Page 66)

3-48 SB3000 Drive Configuration and Programming
3.6 Application Registers (Registers 300-599, Every
Scan) (Registers 1300-1599, Every Nth Scan)
The application registers are used to pass application-specific data between the
AutoMax Processor and the UDC module.
Memory is allocated for a maximum of 600 application registers. There are 300
registers that can be used every scan (registers 300-599) and 300 registers that can
be used every Nth scan (registers 1300-1599). “N” is defined in register 2001. Note
that the status of application registers is not retained after a STOP ALL.
Application registers 300-599 can be used every scan of UDC tasks. Registers within
this range written to by a UDC task are updated by the UDC operating system from its
local memory to dual port memory after each task is run. Registers within this range
written to by an AutoMax task are read by the UDC operating system from dual port
memory and copied into the UDC local memory at the beginning of each scan in order
to have a consistent context for evaluation. See figure 3.1.
Note that the same bits or registers must not be written to (and used as outputs)
by both an AutoMax task and a UDC task.
Application registers 1300-1599 can be used every Nth scan of the UDC task. Nth
scan registers should be used when it is necessary to synchronize one or more UDC
tasks to an AutoMax task.
!
ATTENTION: If you use double integer variables, you must implement a
software handshake between the transmitter and the receiver to ensure
that both the least significant and the most significant 16 bits have been
transmitted before they are read by the receiving application program.
Failure to observe this precaution could result in bodily injury or damage
to equipment.
Figure 3.1 – UDC Task Scan
Input A Run A Output A Input B Run B Output B
UDC Scan*
Feedbac
k From
P
M
I
Com
m
and t
o
PM
I
*Task B can act on Task A outputs within a scan.
Latch “every scan”
registers that are
inputs to task B
Write “every scan”
registers that are
outputs from task A
Latch “every scan”
registers that are
inputs to task A
Write “every scan”
registers that are
outputs from task B