8 relay outputs, expanded temperature range
The Siemens 6ES7322-1HF80-0AA0 is an SM 322 digital output module for the S7-300 family, carrying 8 relay outputs rated for resistive loads up to 8 A per channel and inductive loads up to 3 A. The expanded temperature range variant supports 24 V DC to 230 V AC on the field side, making it a fit for mixed-voltage cabinets where a single module must switch both DC solenoids and AC contactors.
Contact ratings and mechanical life
The relay contacts are rated for 300,000 mechanical cycles. Under load, the cycle count derates: 300,000 cycles at 24 V DC / 2 A, 200,000 cycles at 120 V AC / 3 A, and 100,000 cycles at 230 V AC / 3 A. For a valve bank switching at 1 Hz, that 100,000-cycle ceiling at 230 V AC translates to roughly 28 hours of continuous cycling before the contacts wear out — plan the maintenance interval accordingly. The module draws 125 mA from the L+ supply and 40 mA from the 5 V DC backplane bus. Power dissipation is 3.2 W typical — within the S7-300 rack's thermal budget for a mixed I/O slot.
Physical fit and connector requirement
The module occupies a single S7-300 slot at 40 mm wide, 125 mm tall, and 120 mm deep. It requires a 40-pin front connector (sold separately) for field wiring. The relay outputs are isolated in groups of one channel per group via optocouplers, with 2,000 V AC isolation tested between channels and the backplane bus.