Siemens S7 PLC Connector
Overview
Connects to a Siemens S7 PLC (S7-200/300/400/1200/1500) via the S7NetPlus library, reading and writing PLC memory areas (DataBlock, Input, Output, Memory, Timer, Counter).
Parameters
| Name | Values | Description |
|---|---|---|
| Type | ALLENBRADLEYOMRONTAG | The connector type identifier. |
| IP | IP address or hostname | The IP address or hostname of the PLC. |
| Path | e.g. 1,0 | CIP routing path to the target processor (used for chassis/slot addressing, e.g. through a bridge module). Defaults to 1,0. |
| PLCType | ControlLogix, Plc5, Slc500, LogixPccc, Micro800, MicroLogix, Omron | The controller family being connected to. Defaults to ControlLogix. |
| Protocol | ab_eip, or other libplctag-supported protocol names | The wire protocol to use. Defaults to ab_eip. |
| Timeout | milliseconds (integer) | Per-request timeout for tag reads/writes/initialization. Defaults to 1000. |
| UpdateRate | milliseconds (integer) | How often the connector polls all subscribed tags. Defaults to 1000. |
| ReconnectDelay | milliseconds (integer) | Minimum time between automatic reconnect attempts while the PLC is unreachable. Defaults to 5000. |
Supported Tag Types:
The connector maps onto the standard Industreweb tag types below. For Integer Tag, Decimal Tag, Time Span Tag, and Data Tag - where more than one Allen Bradley elementary type could apply - the specific AB type is selected using a DataType entry in the tag's Parameters. Bool Tag and String Tag don't need this, since each maps to exactly one AB type.
| Tag Type | AB Data Type(s) | Parameters["DataType"] |
|---|---|---|
| Bool Tag | BOOL | Not applicable. |
| Integer Tag | SINT, USINT, INT, UINT, DINT, UDINT, LINT, ULINT | Optional. One of SINT, USINT, INT, UINT, DINT, UDINT, LINT, ULINT. Defaults to DINT if not set. |
| Decimal Tag | REAL | Not currently configurable - always reads/writes as REAL. |
| String Tag | STRING | Not applicable. |
| Date Time Tag | STRING | Not applicable. AB has no native date/time type; the underlying controller tag must be a STRING holding a parseable date/time. Date Time Tags are more commonly used as virtual/system tags (e.g. $DateTime) rather than an actual PLC address. |
| Time Span Tag | SINT, USINT, INT, UINT, DINT, UDINT, LINT, ULINT | Optional, same values as Integer Tag. Defaults to DINT. Represents a plain numeric duration count; the unit (milliseconds/seconds/minutes/hours/days) is set separately via Parameters["DEFAULTUNITS"]. |
| Data Tag | Any of the above, or TIMER (AB TIMER structure: ACC/PRE/DN/TT/EN) | Optional. One of BOOL, SINT, USINT, INT, UINT, DINT, UDINT, LINT, ULINT, REAL, STRING, or TIMER. Defaults to TIMER if not set. |
Note: Integer Tag and Time Span Tag store their value internally as a 32-bit signed integer. If DataType is set to LINT or ULINT, values outside the 32-bit range will be truncated - use a Decimal Tag if the full 64-bit range needs to be preserved.
Note: the AB String data type has a known limitation against Omron controllers - reading/writing a String Tag (or a Date Time Tag, which is backed by String) against an Omron PLC is not currently supported.
Connector Methods
| Name | Arguments | Description |
|---|---|---|
| (none) | - | This connector does not currently expose any custom connector-level methods via Execute Commands. |
Addressing
The Address field of each tag is the fully qualified tag name as it appears in the controller, for example:
- MyTag - a controller-scoped tag
- Program:MainProgram.MyTag - a program-scoped tag
- MyArrayTag[3] - a specific element of an array tag
- MyUdt.MyMember - a member of a user-defined type
The tag name must match the width/type actually configured on the controller - for example, requesting a tag as DINT when it is really an array or a member of a larger UDT will fail to initialize (ErrorOutOfBounds). Where more than one AB type could apply to a tag type (see Supported Tag Types above), set Parameters["DataType"] to match the controller's actual configuration.
Diagnostic Codes
| Code | Type | Description |
|---|---|---|
| 1010 | Error | Unsupported tag type encountered while creating a handle |
| 1015 | Error | A tag's DataType is a 64-bit type (LINT/ULINT) but stores as Int32 - large values will truncate |
| 1020 | Error | Unrecognised DataType for a tag - falling back to the type's default |
| 1025 | Error | Unable to initialize a tag added while the connector was already running |
| 1030 | Error | Unable to create the underlying AB tag handle |
| 1200 | Error | Unable to initialize a tag during the initial connect/reconnect probe |
| 1215 | Error | A reconnect attempt did not bring any tag online |
| 1225 | Error | No tags came online against the PLC on startup |
| 1305 | Error | A tag read returned a non-Ok status |
| 1310 | Error | Exception while reading a tag |
| 1405 | Error | AB tag handle not present for a tag ChangeData was called on |
| 1410 | Error | Write skipped - tag has never successfully initialized against the PLC |
| 1415 | Error | A tag write returned a non-Ok status |
| 1420 | Error | Exception while writing a tag |
| 1510 | Error | RunMethod called with an unrecognised method name |
| 1600 | Error | Exception while disposing an AB tag handle during shutdown |
| 1700 | Error | Unrecognised PLCTYPE configuration value - falling back to the current default |
| 1705 | Error | Unrecognised PROTOCOL configuration value - falling back to the current default |
| 2201 | Debug | Connection lost |
| 2230 | Debug | Invoking Connected |
| 2231 | Debug | Invoking ConnectionLost |
| 2300 | Debug | ReadUpdate cycle overran cycleDelay |
| 2325 | Debug | UDT auto-discovery could not resolve this tag - falling back to raw bytes (reason given in message text) |
| 2400 | Debug | ITag not present - ChangeData called for an unregistered tag name |
| 3100 | Info | Connector started |
| 3205 | Info | Attempting to reconnect to the PLC |
| 3210 | Info | Reconnected to the PLC |
| 3220 | Info | Connected to the PLC on startup |
| 3326 | Info | UDT auto-discovery resolved a tag to a named-field template (template name/id/field count/size given in message text) |