Using the Opto 22 SNAP PAC Driver Module

Click here for Using the Opto 22 SNAP PAC Driver Module tips.

The Driver module is designed to scan either:

• The tags you identify in a special stPublicListOfStrategyTags table, or
• All tags in the Opto 22 device.

For best performance, we strongly recommend you use the stPublicListOfStrategyTags table to get tags.

If you're familiar with Ignition and PAC Control...

1. In the PAC Control strategy:
   1. Create the stPublicListOfStrategyTags table.
   2. Immediately after Block 0 in the Powerup chart, add an OptoScript block.
   3. In the OptoScript block, populate the table according to the OptoScript Syntax and tag naming standard. 
   4. Save, download, and run the strategy.
2. In Ignition:
   1. Restart the SNAP PAC Driver to refresh the tag list. 
   2. Browse the Opto 22 tags and use them in your project. 

Step-by-step instructions

For help using PAC Control, see the PAC Control User's Guide (available from the Opto 22 website).

Create the stPublicListOfStrategyTags table

1. In PAC Control, open your strategy in Configure mode.
   
2. In the Strategy tree window, right-click the String Tables folder, and then click Add. The Add Variable dialog box opens. Complete the fields.
   
   Name:  Enter the table name: stPublicListOfStrategyTags. The name is case-sensitive.
   Description:  Optional.
   Type:  Leave the default (String Table).
   Initialization:  Select Persistent
   Initial Value:  Leave the default (blank).
   Table Length:  Enter a number equal to or greater than the number of tags to import. For example, to import 10 floats and 6 tables, enter a Table Length of 16 or more. (A table variable counts as one tag, despite the number of elements it has.) 
                            Note: Ignition Edge has a limit of 500 tags. Ignition Enterprise does not limit the number of tags you can use
   String Width:  Enter a value of 100.
   
   
3. Click OK to close the dialog box and save your changes.

Add an OptoScript block for the tag list

1. Open the Powerup chart.
   
2. Immediately after Block 0, connect an OptoScript block to the flow.
   

Populate the stPublicListOfStrategyTags table

1. Double-click the OptoScript block to open it.
   

2. For each tag to be scanned, create a string element following the OptoScript Syntax and tag naming standard.
   IMPORTANT: Index number 0 (zero) must be the last item initialized in the OptoScript block

/*
If the tag begins with an ' or a /, the tag is ignored.
Important! Initialize the first table element (at Index 0) last (because 
a blank string in Index 0 tells the driver that the
string table has not yet been initialized).
*/
stPublicListOfStrategyTags[0] = "";
stPublicListOfStrategyTags[1] = "f32.MyFloat.rw";
stPublicListOfStrategyTags[2] = "i64.MyInt64.rw";
stPublicListOfStrategyTags[3] = "s.MyString.rw";
stPublicListOfStrategyTags[4] = "t.MyTimer.rw";
stPublicListOfStrategyTags[5] = "i32b.MyBool.rw";
stPublicListOfStrategyTags[6] = "i32t.MyInt32Table[0-9].rw";
stPublicListOfStrategyTags[7] = "i64t. MyInt64Table [0-20].rw";
stPublicListOfStrategyTags[8] = "f32t.MyFloatTable[10-19].rw";
stPublicListOfStrategyTags[9] = "st. MyStringTable [0-9].rw";
stPublicListOfStrategyTags[10] = "dio.MyDiscreetPoint";
stPublicListOfStrategyTags[11] = "aio. MyAnalogPoint.rw";
stPublicListOfStrategyTags[12] = "i32te.MyInt32TableElement[5].rw";
stPublicListOfStrategyTags[13] = "i32tebp.MyInt32TableElementBitPick [9].2.rw";
stPublicListOfStrategyTags[14] = "i64tebp. MyInt64TableElementBitPick [5].8.rw";
stPublicListOfStrategyTags[16] = "i32bp.MyInt32BitPick.1.rw";
// Remember, initialize index 0 last!
stPublicListOfStrategyTags[0] = "i32.Int32.rw";

In the OptoScript block, you:

• Reference each tag as a string element of the stPublicListOfStrategyTags table (see OptoScript Syntax). 
• Modify each PAC Control tag name according to pre-defined naming standards so the scanner can identify the tag (see Naming Standard).

OptoScript Syntax

stPublicListOfStrategyTags[<index number>] = "<modified tag name>";

stPublicListOfStrategyTags[1] = "s.MyStringVariable";

To construct the tag name, see Naming Standard.

• Index number 0 (zero) must be the last item initialized in the OptoScript block.
• Index numbers must be unique.
• Syntax is case-sensitive.

Naming standard

In the OptoScript block, you reference PAC Control tags using a pre-defined naming standard that consists of the tagís:

• Data type code
• PAC Control tag name
• Index number (Table elements only)
• Bit location (Bit-picks only; 0 is the first bit)
• Writeable attribute (Writeable tags only)

Notes

• Strong-typed OPC tables are not supported.
• Tag names are case-sensitive.
• To comment out a tag (for example, to disable a tag without having to modify the entire string table), prepend a / (slash) or ' (single straight quote mark) to the OptoScript tag name.
  EXAMPLES

  /i32.MyIntVariable.rw
  's.MyStringVariable

Naming standard:  <OptoScript data type code>.<PAC Control tag name>[<index number or range>].<bit location>.< writeable attribute>

Examples:

1. Click Save to close the OptoScript block and save the changes.
   

Save, download, and run the strategy

1. Go into Debug Mode.
2. Save, download, and then run the strategy. 
   
   

Refresh Tag List and Browse Tag Values

1. To refresh the tag list, go to Ignitionís Configure tab, and select System > Modules. In the Cirrus Link Solutions section, restart the Opto 22 SNAP PAC Driver module. When prompted, click Confirm.
   Note: The tag names displayed in Ignition will be different but easily recognizable.
2. To browse tag values:
   From Ignition's Configure tab: Select OPC Connections > Quick Client, and then expand the folders to find the tags from the Opto 22 device's tags.
   
   From Ignition Designer's Design Mode: In the menu bar, click View > Panels, and then select OPC Browser. In the OPC Browser panel, expand the folders to find the Opto 22 device's tags.
   
   

Troubleshooting

TIP: If you canít find a tag, check the following:
* The strategy is running in PAC Control.
* You correctly entered the tag name in the stPublicListOfStrategyTags table.
* After making changes to the table, you restarted the Driver module in Ignition and waited for its status to change to Connected.
For more information, see the Ignition Logs.

Scanning All Tags

If the Driver module canít find the stPublicListOfStrategyTags table in the strategy, it automatically retrieves the strategyís inventory of all driver-supported tags in their native format. This means that PAC Control's object inventory will not match Ignitionís object inventory. (For example, a 32-bit integer in PAC Control may be used as a number, a bitmask, and a zero/non-zero Boolean value.) For performance reasons, we strongly discourage scanning all tags.