Watchdog
This output channel is equipped with a safety device (watchdog). This moves the output to a predefined setpoint if process data traffic to the output device is interrupted.
The watchdog time, i.e. the time at which the watchdog case is triggered, is set via the general TwinCAT dialog "Advanced Settings" -> General -> Behavior -> Watchdog -> "Set Multiplier" and "SM Watchdog" (SM = SyncManager).
This setting applies to the entire device (all channels).
WatchdogTime [ms] = Multiplier * SM Watchdog [ms]
A maximum watchdog time of 65 s is possible. Larger values are calculated modulo 65, for example 70 s would be shortened to 5 s.
Notice | ||
 | General notes on watchdog settings Observe the general notes on the watchdog settings. | |
The procedure is as follows:
- As long as the channel is properly and regularly supplied with EtherCAT process data, they are output. The so-called watchdog observes this without further action; they say "it is being brought up".
- As soon as the data no longer arrives (e.g. due to a wire break, EtherCAT master stopped, etc.), the output value remains at the last value. The watchdog now starts to run down. If data arrive again in time, the watchdog returns to the start value.
- If the watchdog has expired, i.e. the time set as above has elapsed without new data arriving, the substitute value is output.
- As soon as new data arrives and the EtherCAT SubDevice is back in OP mode, it is output again and the watchdog starts monitoring again.
The following settings can be made for the watchdog, starting from index 80n0:05 "Watchdog Type":
Values Index 80nD, | Meaning |
|---|---|
Default watchdog value (default) | The analog output value is set to the user-specific setpoint according to index 80n0:13 or index 80nD:1A without transition (default: 0) |
Watchdog Ramp | Likewise setpoint according to index 80n0:13 or index 80nD:1B, but linear ramp. The ramp slope must be specified in relation to AEWnom |
Last Output value | Last output value remains |
Each watchdog case is counted in index 90n0:05 "Watchdog Counter" (secured against power failure).
Note: as the watchdog is a device property, it is displayed for each output channel but has the same value for all channels. When a watchdog counter is reset, all other channel-specific watchdog counters are also reset.
The counter is reset
- by the command x403n to index FB00:01 (channel1: n=0, channel 2: n=1, ...), the success is displayed with "255" in index FB00:03 Response.
- and by command x4001 "Reset all AO counters"
During command execution, "Status" 255 "busy" is displayed in index FB00:02, "0" means "successfully completed"
The firmware responds to an unknown command with
