Frequently Asked Questions

Why do I get a "Channel Offline Cannot Talk" error message when the ABCLX driver is coming online?

There can be several reasons why ABCLX driver cannot bring its devices online at startup. You should initially confirm that the Boards, Ports and I/O Devices dialog boxes are filled out correctly. You should also confirm that you have enough idle time in your PLC program to allow communication requests to take place.

For details on how to diagnose this problem, search the Knowledge Base page of the AVEVA™ Knowledge & Support Center (located at https://softwaresupport.aveva.com/) for article 000028396 ABCLX Does Not Come Online. This article also includes information about parameter settings and adjustments that might impact this process.

Why does it take so long for the ABCLX driver to come online?

When the ABCLX driver attempts to bring devices online, it initiates a process of downloading and subscribing the required tags from the associated devices. If a project has many tags, this process can overlap with driver polling, causing unnecessary delays. Insufficient idle time in the PLC processor can also cause Plant SCADA driver requests to be prolonged unnecessarily.

For details on how Plant SCADA brings the ABCLX driver online, search the Knowledge Base page of the AVEVA™ Knowledge & Support Center (located at https://softwaresupport.aveva.com/) for article 000028384 How Does Plant SCADA Bring ABCLX Online?.

Every time I start Plant SCADA, I see a nuisance hardware alarm for my ABCLX device that becomes inactive after about 30 seconds. How do I stop this happening?

Hardware alarms are generated by Plant SCADA whenever InitUnit times out or reports and error. In the case of ABCLX driver, this can occur because the required tags have not downloaded and completed subscription.

As a result, there is no workaround or solution for suppressing this hardware alarm. However, the speed at which a driver comes online can be impacted by network bandwidth, PLC CPU utilization, and the number of tags and the number of bad tags.

Search the Knowledge Base page of the AVEVA™ Knowledge & Support Center (located at https://softwaresupport.aveva.com/) for article 000028396 ABCLX Does Not Come Online and article 000028384 How Does Plant SCADA Bring ABCLX Online?.

Using CTAPI to read tags from an ABCLX device causes blank tags to appear.

Using CTAPI to read tags from a device using the ABCLX driver causes the first tag to display its value correctly, but the rest to appear blank. This is caused by request block changes in CTAPI.

To resolve this, change the Protdir.dbf entry for ABCLX from a Max_Length of 2048 to 2032, and Bit_Block from 2048 to 2032 on all Plant SCADA computers on the system. This allows the requested tags to be read correctly; however this reduces the maximum request length from 256 bytes to 254 bytes, which reduces the maximum size of arrays and strings.

Make this change to the protdir.dbf file in the \AVEVA Plant SCADA 2020 R2\bin and the \AVEVA Plant SCADA 2020 R2\user\include directories.

For more details, search the Knowledge Base page of the AVEVA™ Knowledge & Support Center (located at https://softwaresupport.aveva.com/) for article 000028460 Using CTAPI with ABCLX Causes First Tag to Display Its Value Correctly but the Rest of the Tags Appear Blank through CTAPI.

Is it possible to address ControlLogix multidimensional arrays in Plant SCADA if the total length does not exceed 256 bytes?

The ABCLX driver supports multi-dimensional arrays of up to three dimensions.

The I/O device does not come online and the "Channel Offline" error is reported

The v18 and v19 firmware revision onwards by Rockwell for its Logix5000 series processors contain changes in the communications protocol between the SCADA and the PLCs. In some circumstances these changes result in the inability for Plant SCADA to communicate with the controller (PLC) and bring tags online using the ABCLX driver version v3.04.16.000 or later. In certain situations, where ABCLX driver configuration is all correct and during runtime Kernel -> Driver page (ABCLX) confirms that there is no bad tags at all and all configured tags are successfully subscribed, still ABCLX fails to bring the device (unit) online and keeps flickering between Starting and Offline states with Init Timeout count increments.

Solution:

In this situation, make sure External Access is granted (Read or Read/Write) for all tags including Add-On Instructions (AOI) and User-Defined data type (UDT) structure elements in the PLC project. If this is not the case or this cannot be cross-checked, please follow these steps to resolve the issue.

1. In RSLogix5000 project, select Tools > Export > Tags. Ensure that the file name follows the naming convention of PLC_PROJECT_NAME-Tags.csv and that the Tags and Logic Comments fields are both set to All.

2. Copy the tag export CSV file into the main SCADA project directory. The ABCLX driver will search for this file in that location only.

3. Once the CSV file is put inside the SCADA project folder, compile the project and run.

   Please note that despite the fact External Access is granted (not set to None) for all the tags including Add-On Instructions (AOI) and User-Defined data type (UDT) structure elements in the PLC project, the ABCLX driver log still records following traces (error):

   2020-12-06 14:14:03.081 +10:00 [TRACE] [EIP ] [0x00005b78] [ProcessPLCProjectName()] Attempting to open tag export CSV file C:\ProgramData\AVEVA Plant SCADA 2020 R2\User\UDT_Test1\NewTest-Tags.csv 2020-12-06 14:14:03.081 +10:00 [ERROR] [EIP ] [0x00005b78][ProcessPLCProjectName()] Tag export CSV file C:\ProgramData\AVEVA Plant SCADA <VersionNumber> \User\UDT_Test1\NewTest-Tags.csv could not be open, the I/O device may not be able to connect due to tags with no external access .

   Please ignore these messages as long as it is confirmed that External Access is granted (not set to None) to all tags including Add-On Instructions (AOI) and User-Defined data type (UDT) structure elements in the PLC project. If this is not the case, please follow the above-mentioned steps.

For more details, search the Knowledge Base page of the AVEVA™ Knowledge & Support Center (located at https://softwaresupport.aveva.com/) for article 000030309 ABCLX does not bring the device (unit) online and reports 'channel offline' error.