One noteworthy implementation of the Logix driver is how boolean arrays are handled. Boolean arrays items are browsed as members of a 32-bit DWORD. Thus, a BOOL in the PLC is implemented as DWORD in the driver.
Below is a table representing how members of a boolean array items are mapped in the PLC, compared to the Logix driver's implementation.
|PLC Mapping||Driver Implementation|
Device Connection Settings
The General settings are common to all Allen Bradley devices, and the Connectivity settings are device dependent.
The user-defined name for this Device. The name chosen will show up in OPC Item Paths and under OPC-UA Server > Devices of the Configure page of the Gateway. The Device Name must be alphanumeric.
|Description||The user-defined description for the device. This is only used as a note to differentiate between devices.|
|Enable Device||Only devices that are enabled appear in Connections > Devices of the Status page of the Gateway and thus have their tags available for use.|
This is the IP Address of the ControlLogix Ethernet module (1756-ENET) to route through to connect a ControlLogix processor. EthernetIP protocol on TCP port 44818 (0xAF12) is used to communicate to ControlLogix processors.
Port to connect to the remote device.
|Timeout||After sending a request to the ControlLogix processor, the Communication Timeout setting is the amount of time in msec to wait for a response before treating it as a failure.|
|Max Concurrent Requests||The number of requests that Ignition will try to send to the device at the same time. Increasing this number can sometimes help with your request throughput, however increasing this too much can overwhelm the device and hurt your communications with the device.|
|Slot Number||The Slot Number value is the zero based ControlLogix chassis slot number of the ControlLogix processor to connect to.|
Monitor for tag additions and UDT changes and automatically initiate a re-browse when detected. If this is disabled tags will only be browsed when connecting and reconnecting. (Default is true.)
|Identity Request Frequency|
Frequency, in milliseconds, that the request to read CIP Identity Object attributes occurs at. (Default is 5,000.)
|CIP Connection Size|
The CIP connection size to use during Forward Open requests. (Default is 500.)