Using Auto-Clear - Omron SYSMAC CS Series Operation Manual

Operating the Network
6-6-4

Using Auto-CLEAR

Auto-CLEAR Feature
Enabling Auto-CLEAR
Transition Conditions
Note
Resume OPERATE mode
after Auto-CLEAR
1,2,3...
The CS1/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 Mas-
ter will instead send either empty output data messages or output data mes-
sages containing all zeros.
The Auto-CLEAR function can only be enabled through CX-Profibus. The
controls to enable it can be found in the CS1/CJ1W-PRM21 Master DTM -
Master Setup tab (see section 6-4-1 Setting the Master Parameters).
Note The Auto-CLEAR function will only be active if the Master Unit has been
switched to OPERATE mode.
An automatic transition to CLEAR mode will take place in the following situa-
tions.
1. 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 6-4-2 Set-
ting the Bus Parameters), will cause the Master Unit to switch to CLEAR
mode.
2. 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.
1. 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
3-5-1 Configuration User Interface, Extensions Tab), will not cause a tran-
sition to Auto-CLEAR, not even when they fail on the network.
2. 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 6-4-2 Setting the Bus Parameters). Increasing
the Watchdog time will consequently increase the Data Control Time
The CS1/CJ1W-PRM21 PROFIBUS DP does not automatically resume nor-
mal operation after an Auto-CLEAR has been initiated. In order to resume
normal I/O data exchange, perform the following sequence.
1. Determine which slave device failed during network startup or data ex-
change. To do this, use the CS1/CJ1W-PRM21 Master DTM Monitoring
User Interface or the slave DTM (see sections 6-7-1 Monitoring the Master
Unit and the Network and 6-7-2 Monitoring Slave Status) to determine the
slave and its type of failure.
2. Remove the cause of the failure.
3. Press the OPERATE Button in the Master Units Monitoring window.
Alternatively, the Master can also be switched to OPERATE from the PLC
program.
Section 6-6
189