Rockwell Automation 61C365 4 Output 4-20mA Analog Rail - Manual (Page 30)

4Ć8
4.1.3 AutoMate Programming in Local Head Mode
In Local Head mode, the module is imaged in four I/O registers of
the processor. Data from all four channels is always available and
will be updated at the end of each scan. For the output channels,
the data in the register must be in the format shown in figure 4.7
prior to the I/O update.
17 16 15 14 13 12 11 10 7 6 5 4 3 2 1 0 Octal
12 bits of analog output data
not used
not used
not used
not used
Figure 4.7 Ć Local Head Register Image for Output Channels
The Analog Rail module data may also be accessed in the middle of
the scan (as opposed to the end of the scan) using the appropriate
number of Analog Out (AOUT) blocks. See section 4.1.4 for more
information about the AOUT block.
Note that the AOUT block is supported for the AutoMate 20E
(M/N 45C224 and 45C225), but not the AutoMate 20 (M/N 45C20,
45C21, 45C220, 45C221) by APX Version 3.0.
For processors that do not support the AOUT block, you can use
the MOVE block to move data in and out of the registers assigned.
The I/O update will occur automatically at the end of each scan. See
Appendix C for a sample AutoMate program that writes to the
Analog Rail module without using AOUT block.
4.1.4 Analog Out (AOUT) Instruction Block
The AOUT block is used to write outputs to the Analog Rail module.
AOUT blocks are supported for the 20E processor. The AOUT block
makes it possible to update the channels on the Analog Rail module
during the scan instead of at the end of the scan (the standard
AutoMate I/O update). The block also makes it possible to update all
four channels during the scan in Rail mode, a hardware
configuration which would otherwise allow only one channel on the
module to be updated. The format of the block is shown in
figure 4.8.