IFM Electronic AS interface ProcessLine AC2910 Mode D'emploi page 11

Limited voltage
The device shall be supplied from an isolating transformer having a
secondary Listed fuse rated as noted in the following table.
Control-circuit wire size Maximum protective device rating
AWG
26
24
22
20
18
16
Overcurrent protection
2
mm
(0.13)
(0.20)
(0.32)
(0.52)
(0.82)
(1.3)
ampere
1
2
3
5
7
10
11