Delta RMC101 - Manual (Page 473)

PROFIBUS-DP 5.4
Communications 5-223
1
O + 2*n +
2
Reserved by Sensor DI/O
O + 2*n +
3
Reserved by Sensor DI/O
PROFIBUS-DP has a much larger set of commands than the normal ASCII commands that can
be used in the Command field, although ASCII commands are still available. For a complete
description of using the Command and Data out registers, refer to Command Words for
PROFIBUS-DP Compact Mode.
See also:
Using the PROFIBUS-DP Compact Mode
Compact Mode Input Register Overview
Command Words for PROFIBUS-DP Compact Mode
5.4.7 Message Mode
5.4.7.1 Using the PROFIBUS-DP Message Mode
Message Mode is one of two modes that can be used with the RMC PROFIBUS-DP module. The
other mode is called Compact Mode, which is described in Using the PROFIBUS-DP Compact
Mode. Be sure to read both topics and consider each carefully before choosing the mode you will
use.
Message Mode is so called because it imposes a messaging type interface on PROFIBUS-DP.
That is, PROFIBUS-DP only supports cyclic data transfer between a master and a slave.
However, the RMC has nearly 64K registers, all of which cannot possibly be sent over
PROFIBUS every PROFIBUS scan. Therefore, blocks of these registers can be written to and
read from the RMC by using a messaging mechanism: the request is placed in one block of
registers, and a response is received in the other block of registers.
In addition to the Command and Response blocks of data, there is also a third block of data—the
Status Block—that includes status information that is constantly available. A summary of the
Message Mode register blocks follows:
• Status Block
This is a block of 32 contiguous input registers that are constantly updated by the RMC. The
values will be updated every 2ms when no commands are in progress, and every 6ms when a
command is in progress. This block is otherwise independent from the Command and Response
blocks. The contents of these 32 registers are configurable using the Status Map editor. See
Using the Status Map Editor for details.
• Command Block
This is a block of 64 contiguous output registers. These registers are sent from the PLC or PC to
the RMC constantly via PROFIBUS-DP, however, the last register in this block contains two flag