Struggling Reading arrays of Real using libplctag in .NET

[BartGuy1215]

I thought i was well on my way with a project i'm working on, but I guess not.

The rest of the project works great! This library is really nice, but I've hit a wall on a seemingly simple issue.

Trying to read an array of 1024 Reals from a ControlLogix PLC. Looking at the example code sent with libplctag in C#, here's where I am:

Private _PLC_FIFO_TAG As Tag(Of RealPlcMapper, Single())

Private Sub _CreateFIFOTag()
    ' FIFO tag array is fixed at 256 of type display_fifo_entry = 1024 total
    _PLC_FIFO_TAG = New Tag(Of RealPlcMapper, Single())() With
    {
        .Protocol = libplctag.Protocol.ab_eip,
        .Name = "test_array",
        .Gateway = "172.16.1.2",
        .PlcType = PlcType.ControlLogix,
        .Path = "1,0",
        .Timeout = TimeSpan.FromMilliseconds(5000),
        .ArrayDimensions = New Integer(1024)
    }
    _PLC_FIFO_TAG.Read()
End Sub

The .ArrayDimensions initializer is not correct and I can't figure out what it's looking for. Intellisence says it needs an array of integers, but I don't see how that can be the case. Except for C# code I can't find an example that explains the issue.

Any help would be appreciated!

John

[timyhac]

Your float array in the PLC is a one dimensional array of length 1024, so the array dimension property should be {1024}.

[BartGuy1215]

Understood. Here's where I landed with a piece of test code that I wrote to prove the concept.

Tag in the PLC is array of 6 reals for testing

    _PLC_FIFO_TAG = New Tag(Of RealPlcMapper, Single())() With
    {
        .Protocol = libplctag.Protocol.ab_eip,
        .Name = "TEST_ARRAY",
        .Gateway = "172.16.1.2",
        .PlcType = PlcType.ControlLogix,
        .Path = "1,0",
        .Timeout = TimeSpan.FromMilliseconds(200),
        .ArrayDimensions = New Integer(6 - 1) {}
    }
    _PLC_FIFO_TAG.Initialize()
    _PLC_FIFO_TAG.Value = New Single(6 - 1) {1, 2, 3, 4, 5, 6}
    _PLC_FIFO_TAG.Write()

When stepping through the code .Value has a valid Single array created by the NEW, but after the write is executed exception thrown "errNoData". I will try to get the code this morning and walk through it. I use the NeGet package per your previous advice on another issue which dosent install the source, so i can't walk it back completely.

So it looks like as a general statement, for arrays of one, the code provides storage in Value, for multi dimension arrays, we have to push storage into value? Correct assumption?

John

[timyhac]

Very often, Tag arrays are 1D arrays, but modern Allen Bradley controllers allow you to define 2D or 3D array tags as well. ArrayDimensions is how you tell libplctag the length of the dimensions of Value. i.e. how many dimensions it has, and how long each dimension is.

If, for example, the Tag is not a 1D float array of length 1024, but instead a 3D float array of lengths 8, 8, 8, you would need to configure ArrayDimensions to be 1d integer array of length=3 with value { 8, 8, 8 }.

_PLC_FIFO_TAG = New Tag(Of RealPlcMapper, Single(,,))() With
{
    .Protocol = libplctag.Protocol.ab_eip,
    .Name = "TEST_ARRAY",
    .Gateway = "172.16.1.2",
    .PlcType = PlcType.ControlLogix,
    .Path = "1,0",
    .Timeout = TimeSpan.FromMilliseconds(200),
    .ArrayDimensions = New Integer() {8, 8, 8}
}
_PLC_FIFO_TAG.Initialize()
_PLC_FIFO_TAG.Value = New Single(8,8,8) {...}
_PLC_FIFO_TAG.Write()

[BartGuy1215]

Hello Tim,

Thank you for the feedback, but your example does not compile….

I’ll keep looking….

From: timyhac @.> Sent: Thursday, March 10, 2022 8:37 AM To: libplctag/libplctag.NET @.> Cc: John Bartlett @.>; State change @.> Subject: Re: [libplctag/libplctag.NET] Struggling Reading arrays of Real using libplctag in .NET (Issue #244)

Very often, Tag arrays are 1D arrays, but modern Allen Bradley controllers allow you to define 2D or 3D array tags as well. ArrayDimensions is how you tell libplctag the length of the dimensions of Value. i.e. how many dimensions it has, and how long each dimension is.

If, for example, the Tag is not a 1D float array of length 1024, but instead a 3D float array of lengths 8, 8, 8, you would need to configure ArrayDimensions to be 1d integer array of length=3 with value { 8, 8, 8 }.

_PLC_FIFO_TAG = New Tag(Of RealPlcMapper, Single(,,))() With { .Protocol = libplctag.Protocol.ab_eip, .Name = "TEST_ARRAY", .Gateway = "172.16.1.2", .PlcType = PlcType.ControlLogix, .Path = "1,0", .Timeout = TimeSpan.FromMilliseconds(200), .ArrayDimensions = New Integer() {8, 8, 8} } _PLC_FIFO_TAG.Initialize() _PLC_FIFO_TAG.Value = New Single(8,8,8) {...} _PLC_FIFO_TAG.Write()

— Reply to this email directly, view it on GitHub https://github.com/libplctag/libplctag.NET/issues/244#issuecomment-1063605474 , or unsubscribe https://github.com/notifications/unsubscribe-auth/AYCSQ5Q5HG6MNZLAU3IG3CTU7FRM3ANCNFSM5QJGJOTQ . You are receiving this because you modified the open/close state. https://github.com/notifications/beacon/AYCSQ5SQCJ7FRGQMAQZ43TDU7FRM3A5CNFSM5QJGJOT2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOH5SVJYQ.gif Message ID: @. @.> >

[BartGuy1215]

I think I understand now. Testing in the next hour or two…

Thanks again for the help.

John

Sent from my iPhone

On Mar 10, 2022, at 8:36 AM, timyhac @.***> wrote:

 Very often, Tag arrays are 1D arrays, but modern Allen Bradley controllers allow you to define 2D or 3D array tags as well. ArrayDimensions is how you tell libplctag the length of the dimensions of Value. i.e. how many dimensions it has, and how long each dimension is.

If, for example, the Tag is not a 1D float array of length 1024, but instead a 3D float array of lengths 8, 8, 8, you would need to configure ArrayDimensions to be 1d integer array of length=3 with value { 8, 8, 8 }.

_PLC_FIFO_TAG = New Tag(Of RealPlcMapper, Single(,,))() With { .Protocol = libplctag.Protocol.ab_eip, .Name = "TEST_ARRAY", .Gateway = "172.16.1.2", .PlcType = PlcType.ControlLogix, .Path = "1,0", .Timeout = TimeSpan.FromMilliseconds(200), .ArrayDimensions = New Integer() {8, 8, 8} } _PLC_FIFO_TAG.Initialize() _PLC_FIFO_TAG.Value = New Single(8,8,8) {...} _PLC_FIFO_TAG.Write() — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you modified the open/close state.

[BartGuy1215]

Tim,

Thank you again for the help. Issue is solved.

[timyhac]

Awesome, thanks!