Ethercat State Machine - Beckhoff EL3692 Manual

Basics communication
PDI watchdog (Process Data Watchdog)
If there is no PDI communication with the EtherCAT slave controller (ESC) for longer than the set and
activated PDI watchdog time, this watchdog is triggered.
PDI (Process Data Interface) is the internal interface of the ESC, e.g. to local processors in the EtherCAT
slave. With the PDI watchdog this communication can be monitored for failure.
The PDI watchdog is therefore a monitoring for correct and timely process data communication with the
ESC, but viewed from the application side.
Calculation
Watchdog time = [1/25 MHz * (Watchdog multiplier + 2)] * PDI/SM watchdog
Example: default setting Multiplier=2498, SM watchdog=1000 -> 100 ms
The value in Multiplier + 2 corresponds to the number of 40ns base ticks representing one watchdog tick.
Undefined state possible!
The function for switching off the SM watchdog via SM watchdog = 0 is only implemented in terminals from
version -0016. In previous versions this operating mode should not be used.
Damage of devices and undefined state possible!
If the SM watchdog is activated and a value of 0 is entered the watchdog switches off completely. This is
the deactivation of the watchdog! Set outputs are NOT set in a safe state if the communication is
interrupted.
3.4

EtherCAT State Machine

The state of the EtherCAT slave is controlled via the EtherCAT State Machine (ESM). Depending upon the
state, different functions are accessible or executable in the EtherCAT slave. Specific commands must be
sent by the EtherCAT master to the device in each state, particularly during the bootup of the slave.
A distinction is made between the following states:
• Init
• Pre-Operational
• Safe-Operational and
• Operational
• Boot
The regular state of each EtherCAT slave after bootup is the OP state.
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CAUTION
CAUTION
Version: 3.1 EL3692