Digital input modules complement the output modules and provide 2 to 16 channels for reading discrete signals. They connect via the fieldbus adapter but aren’t tied to a specific protocol, so they can work with various GE PLCs. Up to 64 active modules can be daisy‑chained in a single RSTi‑EP station, but the throughput depends on the network bandwidth and system configuration. With limited per‑channel speed and minimal onboard filtering, these inputs are suitable for standard sensor signals but may struggle with very high‑frequency or noisy environments — consider specialized counter modules where needed.