BaseUnit for F-DI modules — fit and function
The 3RK1908-0AP00-0JP0: The housing measures 215 mm tall, 30 mm wide, and 75 mm deep — a slim footprint that takes up three slots on a standard DIN rail.
Voltage and current ratings — what they mean
Rated supply voltage is 24 V DC, with a permissible range of 20.4 to 28.8 V DC. That buys some margin for a sagging 24 V bus or a long cable drop. The base itself is rated for up to 7 A ampacity; that feeds both the module and the loop-through to downstream bases. Insulation voltage is 500 V, surge withstand 6 kV, pollution degree 2 — solid for a control cabinet environment.
Environmental limits
Operation from -25 to +60 °C; above 40 °C you'll need to derate per the manual. Storage and transport go from -40 to +70 °C. Vibration resistance is 15 mm at 6 Hz, 2g up to 500 Hz; shock 6g for 11 ms. That covers most fixed industrial installations without special damping.