Omron CJ Series Operation Manual page 196

5 Operation
 Group Address Setting
User initiated Global-Control commands can be transmitted to either all slave devices allocated to a
Master Unit, or to one or more of up to eight groups of slave devices. The group addresses are
defined by up to eight bits in a group address byte, which is part of the Global-Control command.
Note If a Global-Control command is targeted to all slave devices, all the group bits in the group
address bytes are set to 0.
 Setting the Group Address of a Slave Device
In order for a specific slave device to belong to a certain group, the group assignment for the slave
has to be defined through the Generic Slave DTM Configuration User Interface. A slave device can
belong to one or more groups at the same time, or to no specific group at all. The group assignment
is sent to the slave devices as part of the parameter message.
To define the group assignment of a slave device, through the Generic Slave DTM, refer to section
5-3-3 Selecting the Group Assignment.
 Freeze / Unfreeze commands
Sending a Global-Control - Freeze command to a slave device has the following effect
• The slave device will continue to read its physical inputs, but not send this data to the PROFI-
BUS Master Unit.
• Instead, it will continue to transfer the input data to the Master Unit from the moment the
Global-Control - Freeze command was received.
• If a new Global-Control - Freeze command is sent, the slave device will update its PROFIBUS
input buffers only once with the most recent physical input data and continue to transfer this
data to the Master Unit with subsequent I/O data exchange messages.
• If a Global-Control - Unfreeze command is sent, the slave device will revert back to its original
situation and transfer updated input information to the Master Unit with subsequent I/O data
exchange messages.
Note If a Global-Control command contains both a Freeze and an Unfreeze command, the
Unfreeze will prevail.
The figure shown below illustrates the Freeze / Unfreeze feature as implemented by the CJ1W-
PRM21 PROFIBUS Master Unit.
5-44 CJ-series PROFIBUS Master Unit Operation Manual for NJ-series CPU Unit (W509)