Festo CPV GE-ASI-8E8A-Z M8 Serie Instructions D'utilisation page 21

If by mistake, the same address is assigned to both slaves,
clear access to the slaves is no longer possible. In this case
proceed as follows:
1. Use the address selector button to uncouple slave 1
from the AS−Interface bus.
2. Modify the address of slave 2.
3. Lock the address selector button again, in order to
couple slave 1 to the AS−Interface bus again.
3.3 Assigning the AS−Interface addresses with
addressing devices < Spec. 2.1
Caution
Slave 1 must never have address #31. Otherwise
further modification of the addresses is no longer
possible.
For faultless operation the addresses must be
assigned consecutively (e.g. slave 1: #5; slave 2: #4
or slave 1: #4; slave 2: #5).
Recommendation: Select the addresses so that a
complete byte in the PLC address range is assigned
to the valve terminal.
Festo CPV..−GE−ASI−8E8A−Z M8 0306c English 21