Lenze ESVZAR0 RS-485 - Manual (Page 19)

17 CMVMB401C
Commissioning
7.4 Network Watchdog Timer
The drive is equipped with a network communications watchdog timer. If the Modbus Master wishes to control the
drive (start, forward, reverse, etc.) it must first Unlock Controls (see Section 7.3). If the watchdog timer is enabled
(i.e. P426 is not set to IGNORE) and drive controls have been unlocked, the Master must periodically communicate
with the drive or a watchdog time-out will occur. The watchdog timer does not operate unless Controls have been
UNLOCKED via Register #48 and a time-out action (other than IGNORE) has been specified using parameter P426.
7.5 Watchdog Timer Controls
7.5.1 Watchdog Time-out Period (P425)
The maximum amount of time that should be allowed to pass between network messages to a specific drive will
vary from one network to the next. Therefore, we have made the watchdog time-out period user settable via Drive
Programming Parameter P425 (see 4.1 for details).
7.5.2 Watchdog Time-out Action (P426)
The appropriate action to be taken when a watchdog time-out occurs will also vary from one application to the
next. Therefore, we have provided five user selectable time-out actions which can be set via Drive Programming
Parameter P426 (see 4.1 for details).
If the Watchdog Timer has been disabled (i.e. P426 is set to IGNORE), Controls and/or Parameters must still be
unlocked in order to gain write access to the drive control and/or program parameter registers. However, there are
no longer any constraints on how often the Master must communicate with the drive.