Using Auto-Clear - Omron CJ Series Operation Manual

5
Select the groups to transmit the Global-Control command to.
6
Press the Transmit button to transfer the command to the Unit's CIO area, and to set bit
*_GlobCtlTxCmd in the Software Switches word.
7
The Transmit button will be disabled until the command has been transmitted.
The time between pressing the Transmit button in the CJ1W-PRM21 Master DTM user interface and
the Global-Control command actually being transmitted over the PROFIBUS network will be signifi-
cantly longer than when the Global-Control command is initiated from a CPU user program due to
the additional communication between the PC and the CPU.
5-6-4

Using Auto-CLEAR

 Auto-CLEAR Feature
The CJ1W-PRM21 PROFIBUS Master Units support the Auto-CLEAR function as defined in the
PROFIBUS standard. This feature - when enabled - will switch the PROFIBUS Master Unit to
CLEAR mode automatically, in case one of the slave devices fails on the network. The purpose of
this, is to force the PROFIBUS network to a safe state.
When in CLEAR mode, the PROFIBUS Master Unit will read each slave's input data, but not send
output data. Depending on the slave device, the Master will instead send either empty output data
messages or output data messages containing all zeros.
 Enabling Auto-CLEAR
The Auto-CLEAR function can only be enabled through CX-ConfiguratorFDT. The controls to enable
it can be found in the CJ1W-PRM21 Master DTM - Master Setup tab (see section 5-4-1 Setting the
Master Parameters).
The Auto-CLEAR function will only be active if the Master Unit has been switched to OPERATE
mode.
 Transition Conditions
An automatic transition to CLEAR mode will take place in the following situations.
During network startup at least one slave device rejects its parameter or I/O configuration message
or fails to respond. All slave devices which have already reached data exchange with the Master will
be switched to CLEAR mode again. Also, slave device which remain in not ready state during a time
period which exceeds the Data Control Time (See section 5-4-2 Setting the Bus Parameters), will
cause the Master Unit to switch to CLEAR mode.
After successful network start up, there is no I/O data exchange with at least one slave device for a
period of time which exceeds the Data Control Time.
Slave devices which have either been disabled in the Master Unit, or slave devices for which the
Ignore Auto-CLEAR flag has been set (see section 3-3-1 Configuration User Interface, Extensions
Tab), will not cause a transition to Auto-CLEAR, not even when they fail on the network.
In case a slave device requires more time than the Data Control Time to validate its parameter or
configuration message, premature triggering of Auto-CLEAR can be avoided by increasing the
Watchdog Control Time in the Bus parameter set (see 5-4-2 Setting the Bus Parameters). Increas-
ing the Watchdog time will consequently increase the Data Control Time.
 Resume OPERATE mode after Auto-CLEAR
The CJ1W-PRM21 PROFIBUS DP does not automatically resume normal operation after an Auto-
CLEAR has been initiated. In order to resume normal I/O data exchange, perform the following
sequence.
CJ-series PROFIBUS Master Unit Operation Manual for NJ-series CPU Unit (W509)
5 Operation
5
5-47