x/s7Read component: v0.37.0+ Batch reads point data from Siemens S7 series PLCs (S7-200SMART/300/400/1200/1500). Results are written back to msg.Data and forwarded via the Success chain.

Additional extension library required: rulego-components-iot (opens new window)

Configuration

Field	Type	Description	Default
server	string	PLC address in host:port format; the ISO-on-TCP default port is 102	127.0.0.1:102
rack	int	Rack number	0
slot	int	CPU slot: S7-1200/1500/200SMART=1, S7-300/400=2	1
timeout	int	Request timeout in seconds	5
points	[]object	Default points table; points supplied via msg.Data take precedence when valid	[]

Point fields

Field	Type	Description	Default
name	string	Point name (included in the output for downstream access)	None
addr	string	Siemens address (see syntax below); supports ${msg.xx}	None
type	string	Data type, see options below	None
scale	float	Optional scale factor; engineering value = raw value × scale + offset	-
offset	float	Optional offset	-
endian	string	Optional byte order	-

Point fields

addr field: Uses Siemens address syntax; supports ${msg.xx} template variables.

• DB area: DB<n>.<DBX|DBB|DBW|DBD><offset>[.bit], e.g. DB1.DBD0, DB1.DBW2, DB1.DBX0.1
• M/I/Q areas: word/dword addresses such as MW0, MD0, IW0, QW0; bit addresses such as M0.1

Data type options:

Type	Bytes	Go output type	Description
BOOL	1	bool	Boolean, use a bit address (e.g. DB1.DBX0.1, M0.1)
BYTE	1	byte	Byte
INT	2	int16	Signed 16-bit integer (big-endian)
WORD	2	uint16	Unsigned 16-bit integer (big-endian)
DINT	4	int32	Signed 32-bit integer (big-endian)
DWORD	4	uint32	Unsigned 32-bit integer (big-endian)
REAL	4	float32	32-bit float (big-endian)
LREAL	8	float64	64-bit float (big-endian)
STRING	256	string	S7 string (first byte = max length, second byte = actual length)

Output

Read results are reassigned to msg.Data and forwarded via the Success chain as an array:

Field	Type	Description
name	string	Point name
value	any	Read value; its concrete type depends on the point type
timestamp	string	Read time (RFC3339)
error	string	Error message; empty on success (a single point failure does not affect other points)

Example:

[
  {"name":"temperature","value":25.6,"timestamp":"2026-07-23T10:00:00Z","error":""},
  {"name":"running","value":true,"timestamp":"2026-07-23T10:00:00Z","error":""}
]

Features

• Periodic collection: Place an endpoint/schedule endpoint before this node to trigger it on a schedule, and configure points in points below. For on-demand reads, an upstream node may inject points via msg.Data.
• Template variables: Point fields such as addr support ${msg.xx} / ${metadata.xx} templates.
• Dynamic points precedence: When msg.Data carries a valid points JSON array, it takes precedence; otherwise the configured points are used.
• Chain-scoped connection pool: Other S7 nodes in the same chain may reuse an established TCP connection via ref://nodeID to avoid duplicate connections.
• Failure reconnect/retry: A connection-level failure (all points failed) triggers an automatic reconnect and retry, up to 3 times (maxRetries=3). A single point failure is flagged with an error message and does not interrupt the overall flow.

Relation Type

• Success: Execution succeeds; the message is sent to the Success chain.
• Failure: Execution fails; the message is sent to the Failure chain.

Example

{
  "ruleChain": {
    "id": "s7_read_demo",
    "name": "S7 read demo",
    "root": true,
    "debugMode": false
  },
  "metadata": {
    "firstNodeIndex": 0,
    "nodes": [
      {
        "type": "x/s7Read",
        "name": "Read PLC data",
        "debugMode": false,
        "configuration": {
          "server": "192.168.1.100:102",
          "rack": 0,
          "slot": 1,
          "timeout": 5,
          "points": [
            {"name": "temperature", "addr": "DB1.DBD0", "type": "REAL"},
            {"name": "counter", "addr": "DB1.DBD4", "type": "DINT"},
            {"name": "running", "addr": "M10.5", "type": "BOOL"}
          ]
        }
      }
    ],
    "connections": []
  }
}