# Limit to the amount of parameters in 'list' value source function for OPC Device Simulator Program?

**URL:** <https://forum.inductiveautomation.com/t/limit-to-the-amount-of-parameters-in-list-value-source-function-for-opc-device-simulator-program/44023>\
**Category:** Ignition\
**Created:** [March 3, 2021, 6:09am UTC](https://forum.inductiveautomation.com/t/limit-to-the-amount-of-parameters-in-list-value-source-function-for-opc-device-simulator-program/44023 "2021-03-03T06:09:33Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Jake.Herington](https://avatars.discourse-cdn.com/v4/letter/j/dec6dc/32.png) [@Jake.Herington](https://forum.inductiveautomation.com/u/Jake.Herington)\
**Post date:** [March 3, 2021, 6:09am UTC](https://forum.inductiveautomation.com/t/limit-to-the-amount-of-parameters-in-list-value-source-function-for-opc-device-simulator-program/44023/1 "2021-03-03T06:09:33Z")

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Hello,

I want to load an OPC Device Simulator Program from a csv file using the list value source function. My current csv file has over 3000 parameters in each list function and there is around 400 rows. When trying to load the program I get an ‘Internal Error’.

I realize this is likely way too many parameters causing the error but the manual says the function takes any number of parameters. I would like to know if there’s a limit to the amount of parameters I can have so I can prune my data down or if there’s is a better solution.

Thanks,  
Jake.

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [March 3, 2021, 10:57am UTC](https://forum.inductiveautomation.com/t/limit-to-the-amount-of-parameters-in-list-value-source-function-for-opc-device-simulator-program/44023/2 "2021-03-03T10:57:42Z")

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If you are trying to simulate a Logix device or a Modbus device (or something generic), one of my driver modules will be more flexible than the Device Simulator.

> [@Snappy user interfaces with the Ethernet/IP Module](http://forum.inductiveautomation.com/t/snappy-user-interfaces-with-the-ethernet-ip-module/12617):
>
> Automation Professionals [Ethernet/IP Class1 Communications Module](https://www.automation-pros.com/modulesales.html) has been in beta for a few months with no recent issues. A release to production use is approaching soon and I thought I’d share a test project and its matching PLC code I’ve been using to exercise the module’s base features. In the simplest setup, this driver presents a virtual I/O chassis to to the outside world, populated with up to 100 virtual I/O modules – I/O modules that also appear to be ControlLogix processors with user…

> [@Automation Professionals' Advanced Modbus Driver](http://forum.inductiveautomation.com/t/automation-professionals-advanced-modbus-driver/41312):
>
> Automation Professionals is pleased to announce the first beta for its Advanced Modbus Driver, for Ignition version 7.9. Key features: Server mode, emulating one or more slave [devices](https://www.automation-pros.com/modbus/UserManual.pdf), using any of the three typical connection types, including simultaneous connections of multiple types. Client mode, incorporating all three connection modes in one driver. Support for Modbus Function Codes 20 and 21, File Records. Configure protocol tweaks for troublesome devices per slave unit, enabling suppor…