H1 Slot Time; Duration Of Redundancy Switch-Over; A.2.3 H1 Slot Time - ABB Ability 800xA Series User Manual

A Limits and Performance Data
A.3 Duration of Redundancy Switch-Over
A.2.3

H1 Slot Time

The H1 bus parameter SlotTime has to be less than 50. Otherwise, the maximum
time of inactivity on an H1 link would exceed 200 ms, which in turn would have an
impact on the fault detection time, i. e. a failure in an H1 channel could not be detected
within the currently used fault detection time.
Please note: Certain configurations of bus parameters (SlotTime, MaxResponseDelay,
MinInterPDUDelay) can reduce the possible maximum numbers of republished signals
per second and H1 link.
A.3

Duration of Redundancy Switch-Over

During redundancy switch-over, the activity on H1 links is interrupted. From the
perspective of a single H1 device, publishing or subscribing a process value is interrupted
for a period of time that is composed of the following times:
• fault detection time t
• redundancy switching time t
• macro cycle duration t
The time of inactivity due to redundancy switch-over for a single process value is therefore:
• time of inactivity ≤ t
compared to t
The fault detection time is:
• t
fd
• t
fd
The redundancy switching time is:
• t
rs
The macrocycle duration depends on the configuration and is usually in the range of
200 ms to 1000 ms.
2PAA114135-610
fd
mc
+ t
fd
during regular operation
mc
= 500 ms if the primary device fails.
= 500 ms if the Ethernet connection on the primary device is disconnected.
= 500 ms
rs
+ t
rs mc
95