# system.opc.readValues

**URL:** <https://forum.inductiveautomation.com/t/system-opc-readvalues/8716>\
**Category:** Ignition\
**Created:** [July 11, 2014, 7:52pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalues/8716 "2014-07-11T19:52:51Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Tim](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/tim/32/3361_2.png) [@Tim](https://forum.inductiveautomation.com/u/Tim)\
**Post date:** [July 11, 2014, 7:52pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalues/8716/1 "2014-07-11T19:52:51Z")

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What is the proper syntax to list item Paths when using system.opc.readValues?

I am able to use system.opc.readValue to read one tag, but when attempting to read multiple I receive “TypeError: readValues(): 2nd arg can’t be coerced to String[]”

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<div class="post-metadata">

**Author:** ![nmudge](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/nmudge/32/3394_2.png) [@nmudge](https://forum.inductiveautomation.com/u/nmudge)\
**Post date:** [July 11, 2014, 8:35pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalues/8716/2 "2014-07-11T20:35:59Z")

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The second argument needs to be a list.  
A list looks like this:

```auto
myList = ["path1","path2","path3"]
```

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<div class="post-metadata">

**Author:** ![Tim](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/tim/32/3361_2.png) [@Tim](https://forum.inductiveautomation.com/u/Tim)\
**Post date:** [July 11, 2014, 8:50pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalues/8716/3 "2014-07-11T20:50:17Z")

</div>

`SN = system.opc.readValues('Ignition OPC-UA Server', "[MES_PLC]Global.CarrierInfo.CarrierInfo[0].Serial_Number.STRING]","[MES_PLC]Global.CarrierInfo.CarrierInfo[0].Order_Number.STRING]")
print SN`

I receive “TypeError: readValues(): expected 2 args; got 3”

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<div class="post-metadata">

**Author:** ![nmudge](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/nmudge/32/3394_2.png) [@nmudge](https://forum.inductiveautomation.com/u/nmudge)\
**Post date:** [July 11, 2014, 8:54pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalues/8716/4 "2014-07-11T20:54:32Z")

</div>

The square brackets around the paths are missing. Try this:

```auto
SN = system.opc.readValues('Ignition OPC-UA Server',["[MES_PLC]Global.CarrierInfo.CarrierInfo[0].Serial_Number.STRING]","[MES_PLC]Global.CarrierInfo.CarrierInfo[0].Order_Number.STRING"])
print SN
```