PROFINET IRT at 250 µs — motion-loop timing
The 6ES7155-6AA01-0BN0 is a SIMATIC ET 200AL interface module (IM 155-6 PN BA) that connects distributed I/O to a PROFINET controller. It supports isochronous real-time (IRT) communication with send cycles between 250 µs and 4 ms in 125 µs increments — deterministic enough to close a servo loop on a multi-axis machine without jitter in the cycle. Two RJ45 ports with an integrated switch handle 100 Mbit/s full duplex (100BASE-TX), and the module ships pre-assembled with a BusAdapter BA 2x RJ45. Compatible BusAdapters include BA 2x FC and BA 2x M12 variants if the installation calls for FastConnect or M12 termination.
I/O expansion and diagnostics
Via the BU/BA send interface, the module supports up to 16 ET 200AL I/O modules. Prioritized startup and shared-device functionality let multiple controllers access the same I/O station — useful for safety CPU separation on a single rail. Diagnostics are comprehensive: RUN (green), ERROR (red), and MAINT (yellow) LEDs on the face, plus SNMP, LLDP, and PROFINET alarms. I&M data (I&M0 to I&M3) is supported for asset tracking through the network management tool.
Power draw is 1.9 W typical from the 24 V DC supply. The inrush current peaks at 3.7 A. The I2t rating of 0.09 A²·s is the thermal let-through for the internal electronics — relevant for sizing the upstream 24 V DC breaker if you are coordinating selectivity on the panel's control supply.