Plc 2 Upload/Download Procedures - Allen-Bradley 1779-KFMR User Manual

PLC 2 Upload/Download
Procedures
Set Data Table Size
This command sets the data table size for the PLC-2 processor. Before
you send this command, you must send an enter download mode
command ("Enter Download Mode"). Use this command immediately
before performing any physical writes on the PLC-2 processor.
For the DATA field in this command, enter the number of bytes of
memory that you want to allocate to the PLC-2 data table. Since
programmable controller words are two bytes long, the DATA value is
double the number of words in the PLC-2 data table. The DATA value is
also equivalent to the physical address of the start of the processor's
program memory. To determine allowable data table sizes, refer to the
programming manual for the appropriate PLC-2 processor.
Command Format:
Reply Format:
Unless otherwise stated, values shown are in hexadecimal, and each block
shown represents one byte.
A command application for communication with a PLC-2 station is to
upload and download the contents of the PLC-2 memory. To upload or
download a PLC-2 memory, you must follow the procedures listed here.
Download
Since a download replaces the program, and this replacement may take
several seconds, the PLC-2 processor must be stopped during the
download so that it does not try to execute a program that is changing.
Because the data table may change during a download, the 1779-KP2
interface must prevent other stations from accessing what may be a partial
data table. The interface must also prevent a programming terminal from
accessing the program during a download. The interface will block other
Chapter 8