Rockwell Automation SD3000 Drive Configuration, Programming - Manual (Page 58)

3.5 Application Registers (Registers 300-599, Every Scan)
(Registers 13004599, Every Nth Scan)
The application registers are used to pass application-specific data between an AutoMax Processor
and the UDC module.
Memory is allocated for a maximum of 600 application registers which are used by both tasks (A and
B). There are 300 registers that can be used every scan (registers 300-599) and 300 registers that
can be used every Nth scan (registers 13004599). “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.
W A R N I N G
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 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
Input A R u n A Output A Input B Run B Output B
Latch “every scan”
registers that are
inputs to task A
*Task B can act on Task A outputs within a scan.
L
Latch “every scan”
registers that are
inputs to task B
Write “every scan”
re isters that are
ou puts from task A
Write “eve scan”
registers at
outputs from task B
Figure 3.1 - Typical UDC Task Scan
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-l 599 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.
The registers within this range (13004599) that are written to by a UDC task are updated by the UDC
operating system from its local memory to dual port memory at the end of the scan that occurs
before the Nth scan (N-i). At that time, an interrupt will be generated by the UDC operating system to
indicate that new data has been written to the dual port memory. Refer to the 2000-series registers for
more information on interrupts. An AutoMax task must have defined a hardware EVENT in order to be
able to respond to an interrupt from the UDC module. Registers within this range that are 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 the Nth scan. See figure 3.2.
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