Single node for Modbus TCP read/write operations against PLCs and industrial gateways. On-prem only — not cloud-compatible.
When to use
- Read holding/input registers from Siemens, Allen-Bradley gateways, or RTUs.
- Write coils or registers for setpoints and commands.
- Poll plant equipment on port 502.
Properties
| Property | Type | Description |
|---|---|---|
| IP Address / Host | text | PLC IP. Required. |
| Port | number | Default 502. |
| Unit ID / Slave ID | number | Default 1. |
| Timeout (ms) | number | Default 3000. |
| Register Byte Order | select | Big-endian (Modbus standard) or Little-endian. |
| Operation | select | Read coils/discrete/holding/input; write single coil/register; write multiple registers (FC16). |
| Start Address | number | Zero-based or 4xxxx style address. Required. |
| Count (reads) | number | Number of registers/coils to read. |
| Decode As (register reads) | select | Raw array, UInt16, Int16, UInt32, Int32, Float32. |
| 32-bit Word Order | select | AB CD, BA DC, or CD AB word-swapped. |
| Write Value | text | For single write: true/false or 0–65535. |
| Write Values (FC16) | text | Comma-separated register values. |
Outputs
Decoded values array, raw registers, operation metadata. Dry Run returns synthetic values.
Notes
- Requires network route to PLC; use Approval gates for writes.
- Match byte order with device documentation to avoid garbage readings.