11/2017 - Version 4.5.2
02/2017 - Version 4.5.1
12/2015 - Version 4.5.0
10/2014 - Version 4.4.1
01/2013 - Version 4.4.0
06/2011 - Web Site Update
02/2011 - Version 4.3.1
01/2011 - Version 4.3.0
06/2010 - Version 4.2.1
12/2009 - Version 4.2.0
01/2008 - Version 4.1.1
10/2007 - Using "testplc" for basic communications testing
08/2007 - Replacing A-B INTERCHANGE with PLCIO
08/2007 - Determining array size in a ControlLogix PLC
New PLCIO Version 4.2.1 Released

Version 4.2.1 of the PLCIO communications software is now available. This version includes important fixes for communicating with an Allen-Bradley ControlLogix family PLC that has been upgraded to firmware version 18.

Earlier versions of PLCIO will get a Privilege Violation error when attempting to read or write to a v18 tag. This is due to the new external tag access feature that Allen-Bradley has incorporated into the PLCs.

Full Changelog:

  • Add 'v' operation to the 'testplc' example program. This uses plc_validaddr() to test if a PLC address is valid.
  • Change argument name 'pj_kind' to 'pj_size' in all modules' _plc_validaddr().
  • Add support to the 'cip' module for ControlLogix Firmware v18. This causes the following user-visible changes in behavior:
    • Tags are no longer loaded from the PLC by default. Instead, the first time a particular tag is accessed, PLCIO will read one element from the PLC to determine its type and element-size. If this read did not satisfy the application's read request, or if the request was a write, then a second request is made to fulfill the action.
    • A new option "LoadTags" is introduced to maintain the functionality of loading tags, programs, and user-defined types. The 'showcip' program now uses "LoadTags".
    • When tags are not preloaded, plc_validaddr() will make a query the PLC to determine a tag's element size and check if the tag is accessible.
    • The 'pj_size' argument returned by plc_validaddr() now returns the tag's element size instead of the tag's total size.
    • The default plc_open() timeout for 'cip' is now 5 seconds if "LoadTags" is not specified, or 60 seconds if it is.
    • All tag addresses now only reference global scope unless they are in the form 'Program:Tagname'. The syntax ':Tagname' is still supported for backward compatibility.
    • Multi-dimensional arrays can now be addressed as 'Array[2,3,10]' in addition to 'Array[2][3][10]'.
    • For 2- or 3-dimensional arrays, a new restriction is in place where the application must specify all 2 or 3 indexes to the array.
  • Added new PLC error "PLCE_ACCESS_DENIED" (code 23), to be emitted when remote read/write access to a PLC Address is disabled by a PLC program switch.
  • Use a separate variable in the 'cip' module called "ps_cip->c_loadtags" to determine if tags were preloaded at plc_open() time, rather than rely on "ps_cip->j_num_tags".
  • Fixed the 'showcip' program to show the correct address and structure member of an aliased tag, as displayed in the "Alias For:" column.
  • 'showcip' now displays arrays as TAG[2,3,5] instead of TAG[2][3][5].

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