Delta RMC101 - Manual (Page 474)

RMC100 and RMCWin User Manual
5-224
bits that are toggled to indicate a request. The command block is described in further detail
below.
Note: Users of Compact Mode should be aware that commands issued over Message Mode are
always handled. Specifically this means that if you send a command multiple times it will be
processed every time it is received. Under Compact Mode duplicate commands are ignored. This
means that Compact Mode users who want to re-issue a command (for example, an ’E’ command
to start an event sequence) need to toggle the case of the command (for example, toggle between
’E’ and ’e’).
• Response Block
This is a block of 64 contiguous input registers. These registers are sent from the RMC to the
PLC or PC constantly via PROFIBUS-DP, however, the values will not change unless a new
request was triggered using the flag bits in the last register of the command block. This
mechanism is described below.
Therefore, Message Mode requires 96 input words and 64 output words on the PROFIBUS
master. Not all PROFIBUS masters support this; if your master does not support this many
registers, you will need to use Compact Mode.
Messaging in Greater Detail
The Command Block has the following structure:
Register
Description
0-58 Write Data
59 Write address (0-65,535). See the RMC Register Map
(PROFIBUS-DP Message Mode) topic for a description of all
RMC registers and their addresses.
60 Write length (in words; 0-59)
61 Read address (0-65,535). See the RMC Register Map
(PROFIBUS-DP Message Mode) topic for a description of all
RMC registers and their addresses.
62 Read length (in words; 0-63)
63 Output Synchronization Register:
Bit 15 - Read Request
Bit 14 - Write Request
The Response Block has the following structure:
Register
Description
0-62 Read Data
63 Input Synchronization Register
Bit 15 - Read Acknowledge
Bit 14 - Write Acknowledge
To request a read from the RMC, use the following steps:
• Wait until the Read Request bit is equal to the Read Acknowledge bit. If they are not equal, the
RMC is currently processing a read request.
• Set the Read Address and Read Length output registers. See RMC Register Map (PROFIBUS-
DP Message Mode) topic for a description of all RMC registers and their addresses.
• Toggle the Read Request bit.