Rockwell Automation 2755 Enhanced Decoder Series B - Manual (Page 266)

Chapter
16
Publication 2755-833
PCCC Host Commands
This chapter defines PCCC (Programmable Controller
Communications Commands) commands you can send from a host
to the decoder using the DH485 interface. These commands allow
you to use binary data exchange to configure the decoder, read data
from the decoder, and obtain diagnostic information.
The PCCC host commands use the Allen-Bradley DH485 link
protocol. To use these commands, the Host Protocol configuration
parameter on the Host Communications configuration screen must
be set to one of these options:
•
DH485 PCCC-1 Protocol with Write Replies
•
DH485 PCCC-2 Protocol without Write Replies
The decoder supports the following DH485 communication
addresses:
DH485 LSAP Function
0 Diagnostic Commands (Perform Application Layer)
1 or 128 PCCC Commands (Perform Application Layer)
129 Perform Link Reset-immediate Block
The PCCC commands perform the same functions as the
configuration screens and fall into three categories:
1. Unprotected Read Command The unprotected read command is
used to read bar code data, configuration data, counter values,
performance indicators and the last message sent to host.
2. Unprotected Write Command The unprotected write command
is used to modify (or write over) configuration data, clear
counters, flush data, set defaults, and perform other functions.
3. Diagnostic Command The diagnostic command is used to read
link layer diagnostic counters and statuses, reset diagnostic
counters, and perform a diagnostic loop.
Chapter Objectives
Protocol Options
PCCC Commands