Plc 3 Upload/Download Procedures - Allen-Bradley 1779-KFMR User Manual

Chapter 8
PLC 3 Upload/Download
Procedures
Unless otherwise stated, values shown are in hexadecimal, and each block
shown represents one byte.
A common application for communication with a PLC-3 station is to
upload and download the contents of the PLC-3 memory. To upload or
download a PLC-3 memory, you must follow the procedures listed here.
Download
Since a download replaces the program, and this replacement may take
several seconds, the PLC-3 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-KP3
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
access to the PLC-3 memory during a download if your download
procedure follows this order:
Diagnostic Status (to Determine Whether the Destination Station
Exists)
Download Privilege
Shutdown
Physical Write
.
.
.
Physical Write
Physical Read (Verification)
Restart
Upload
To ensure a stable program image during an upload, the 1779-KP3
interface must prohibit program changes during an upload. The interface
will block other access to the PLC-3 memory during upload if the general
uploading procedure follows this order: