Delta RMC101 - Manual (Page 467)

PROFIBUS-DP 5.4
Communications 5-217
7. Add any other RMC devices you want on the same network. To do this, repeat steps 5 and 6.
8. Save your configuration.
9. Send the configuration to the master device. This step varies depending on the master you
selected.
5.4.6 Compact Mode
5.4.6.1 Using the PROFIBUS-DP Compact Mode
Compact Mode is one of two modes that can be used with the RMC PROFIBUS-DP module. The
other mode is called Message Mode, which is described Using the PROFIBUS-DP Message
Mode. Be sure to read both topics and consider each carefully before choosing the mode you will
use.
Compact Mode uses two 16-bit input registers and two 16-bit output registers per axis. These
registers are described in detail in Input registers and Output registers. The role of PROFIBUS-
DP is to carry the commands given from the master through the Output registers to the RMC100,
and to carry requested data from the RMC100 through the Input registers back to the master.
PROFIBUS-DP achieves this by continually sending these registers back and forth.
Compact Mode gives two choices for synchronizing this data within the PROFIBUS master, called
Compact Mode with Sync and Compact Mode without Sync.
Compact Mode with Sync
This sub-mode provides one additional input and one additional output register called the
Synchronization Input and Synchronization Output registers respectively. In this mode,
commands are not processed by the RMC until the Synchronization Output register changes.
When this register changes, all commands that change on all axes are processed. As a result the
PROFIBUS master’s data-update cycle can be asynchronous with its programming cycle. For
example, some PLCs do not guarantee that the PROFIBUS I/O will be done at the top of the
ladder logic scan. Therefore the input register could change at any time during the PROFIBUS
scan.
The following general steps should be taken in a control program:
• Write all new commands and command values to the Output registers.
• Increment the Output Synchronization Register.
• Wait for the Input Synchronization Register to match the Output Synchronization Register.
• Process data in the Input registers.
• Repeat the process.
Note: When using Wonderware’s InControl with sequential function charts, it is necessary to
increment the Output Synchronization Register in a step by itself, rather than in a step that also
updates the command or command values. The reason for this is that InControl updates all the
output registers at once, and apparently can have the data sent to the RMC100 module in the
middle of updating the block. Therefore, some commands can be separated from their command
values.