Omron SYSMAC CS Series Operation Manual page 208

Operating the Network
Global-Control Sync command
PLC Cycle
PROFIBUS Cycle
Slave Output
Refresh Cycle
Transmitting Global-
Control Commands
PLC User Program
Example
Note If a Global-Control command contains both a Sync and an Unsync command,
the Unsync will prevail.
The figure shown below illustrates the Sync / Unsync feature as implemented
by the CS1/CJ1W-PRM21 PROFIBUS Master Unit.
Instruction Instruction
Execution Execution
Sync
transmitted transmitted
Sync command causes
immediate refresh of
slave outputs, and
freezes slave output
refresh process.
Note The Global-Control command as set in the CIO words is transferred to the
Unit together with the I/O data, but the Global-Control command is sent over
the PROFIBUS network, following the I/O data. This means that the outputs of
the targeted slave device will be updated with the values sent to the slave
prior to the Global-Control command.
In order to transmit a Global-Control command the user has to define the
group address and the command (e.g. Freeze, Sync). These two parameters
must be entered in Global-Control command word (CIO Word n+2, see sec-
tion 4-2-2 Global-Control Message (Word n+2)).
After setting these parameters, the Global-Control command must be trans-
mitted over the PROFIBUS network. This is accomplished by setting the
Transmit Global-Control command bit (bit 04) in the Software Switches 1 word
(CIO Word n, see section 4-2-1 Software Switches 1 (Word n)). Setting this bit
will transmit the message only once. After transmission has been completed,
bit 04 in the Software Switches 1 word will be reset again.
Transmitting a Global-Control command from a PLC user program can be
accomplished using the steps described above.
Below is an example ladder program, which transmits one Global-Control -
Freeze command to Group 2. The unit number for the example Unit is 0.
Global-Control Unsync command
Instruction
Execution
Sync
Sync command causes
immediate refresh of
slave outputs with last
received PROFIBUS
output data.
Section 6-6
Instruction
Execution
Unsync
transmitted
Unsync command
cancels Sync command
and causes immediate
refresh of slave outputs
and with last received
PROFIBUS output data.
187