Modbus Tap

Read Modbus-TCP PLCs — holding/input registers (FC03/FC04) and coils/discrete inputs (FC01/FC02) with decode hints (uint16/int16/uint32/int32/float32), plus a warn/alarm threshold health summary. Covers many domestic 国产 controllers (汇川/信捷/和利时/台达) and any vendor speaking Modbus-TCP. Use when the task names Modbus, a register/coil address, or unit/slave id. Routes to the ot-aiops MCP server. Read-only. For OPC-UA/S7/Mitsubishi/MTConnect/MQTT use the sibling *-tap skills; not for IT/network gear, Kubernetes, hypervisors, or backups.

Read-only Modbus-TCP telemetry via the ot-aiops MCP server. Preview — validated against a mocked pymodbus client, NOT live PLCs.

When to use

• A PLC speaking Modbus-TCP (host:502, unit_id), incl. domestic 国产 PLCs.
• Read registers/coils; classify registers against thresholds.

When NOT to use (routing)

• OPC-UA → opcua-tap; Siemens S7 → s7-tap; Mitsubishi → mc-tap; CNC → mtconnect-tap; MQTT/UNS → sparkplug-tap; cross-protocol triage → industrial-diagnostics.
• IT/network devices, Kubernetes, hypervisors, backups → not this tool.

Tools

Tool	Params	Returns
modbus_read_holding	address, endpoint?, count=1, decode="uint16"	{raw_registers, decoded[...]}
modbus_read_input	address, endpoint?, count=1, decode="uint16"	{raw_registers, decoded[...]}
modbus_read_coils	address, endpoint?, count=1	{bits[bool,...]}
modbus_read_discrete	address, endpoint?, count=1	{bits[bool,...]}
modbus_health_summary	endpoint?, addresses[]?, thresholds?, register_type="holding"	{overall, counts, offenders[...]}

Registers are untyped 16-bit words; pick decode. Word order is big-endian.

Example

modbus_read_holding(address=0, endpoint="plc2", count=2, decode="float32") → {"address":0,"count":2,"decode":"float32","decoded":[20.0]}

Setup

ot-aiops init (add a modbus endpoint) · ot-aiops doctor · ot-aiops mcp.

Safety

Read-only (FC05/06/15/16 writes are NOT implemented). Device text sanitized; secrets never returned. 缺功能提 issue/PR 欢迎留言.