Predefined System tags are located in the _Attributes subgroup of the device and use the reserved key word $SERVER as the address. Predefined System tags provide status and control information for a given Device.
If desired, individual System tags can be removed, or the entire _Attributes subgroup can be deleted from the Project Workspace.
|
Tag Name |
Data Type |
Access |
Description |
|
_DeviceTimeout |
VT_I2 |
READ / WRITE |
Device Timeout setting. Writing this tag will change the device Timeout (ms) setting in the Device Properties Also See: Configuring Server Devices
|
|
_DeviceType |
VT_BSTR |
READ ONLY |
Reports the controller style the device is configured as from the Device Properties. Also See: Configuring Server Devices
|
|
_DriverName |
VT_BSTR |
READ / WRITE |
The current driver name applied to the device. Writing to this tag will Hot Switch Drivers to a different communication driver used by the device. The value for the tag must be a valid driver name configured in the OPC Server. By using the name of a configured driver, the OPC Server can perform a change over to a different network, or completely different driver. For Example: It is possible to hot switch drivers from Ethernet to Data Highway Plus to Serial DF1 and back again. Also See: Configuring Server Drivers
|
|
_Enabled |
VT_BOOL |
READ / WRITE |
Enables or Disables the communications to the device Writing (0) FALSE to this tag will cause the OPC Server to suspend communications to the device. All tags from the device will change quality codes to QUAL_UNCERTAIN. Writing (1) TRUE to this tag will cause the OPC Server to resume communications to the device. Tags from the device will be update with current values and quality codes
|
|
_ErrorCode |
VT_I4 |
READ ONLY |
Most recent error reported by the device. Also See: Error Codes
|
|
_MessageCount |
VT_I4 |
READ ONLY |
Running count of messages sent and received by the device.
|
|
_MessageErrors |
VT_I4 |
READ ONLY |
Running count of errors the reported by the device
|
|
_MessageRecv |
VT_I4 |
READ ONLY |
Running count of reply messages received from the controller.
|
|
_MessageSent |
VT_I4 |
READ ONLY |
Running count of messages sent to the controller |
|
_Node |
VT_BSTR |
READ WRITE |
Current PLC Node, CPU / CIP Route path the device is using from the Device Properties.
Writing to this tag, will Hot Switch Nodes to another PLC Node, CPU, or CIP Route path.
|
|
_ResetCounts |
VT_BOOL |
READ WRITE |
Resets values in _MessageCount, _MessageErrors, _MessageRecv and _MessageSent
|
|
_Simulate |
VT_BOOL |
READ WRITE |
Toggles device Simulation mode
Writing (1) TRUE to this tag will place the OPC Server in Simulate Mode Writing (0) FALSE to this tag remove Simulate Mode
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