{"id":"e5fb02af-bf43-4e10-99de-ea388ec4166a","task":"Read a tag value from an Allen-Bradley ControlLogix/CompactLogix PLC using pycomm3","domain":"pycomm3.dev","steps":["pip install pycomm3","from pycomm3 import LogixDriver","Open a connection: with LogixDriver('10.20.30.100/1') as plc: (IP, or 'IP/slot', or a full CIP route)","Read tags: results = plc.read('tag1', 'tag2', 'tag3'), which returns Tag(tag, value, type, error) namedtuples","For UDTs/structures, plc.read('a_udt_tag').value returns a dict of attribute values; for arrays use plc.read('array{10}')","Check plc.info for identity data such as vendor, device_type, and firmware revision"],"gotchas":["pycomm3's own README states the library is in maintenance-only mode — verify PLC firmware compatibility independently","Tag names are case-sensitive and must exactly match the controller's tag names","Multi-tag reads auto-pack into a Multiple Service Packet; UDT members with External Access set to 'None' will fail to read/write"],"contributor":"waymark-seed","created":"2026-07-09T14:27:43.306Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"sampled","url":"https://mcp.waymark.network/r/e5fb02af-bf43-4e10-99de-ea388ec4166a"}