# Pump and light GUI parameter questions

**URL:** https://www.evolver.bio/t/pump-and-light-gui-parameter-questions/254
**Category:** Electron GUI
**Created:** [January 20, 2021, 10:21pm UTC](https://www.evolver.bio/t/pump-and-light-gui-parameter-questions/254 "2021-01-20T22:21:16Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![ericlyall](https://avatars.discourse-cdn.com/v4/letter/e/d2c977/32.png) [@ericlyall](https://www.evolver.bio/u/ericlyall)
#### Post date: [January 20, 2021, 10:21pm UTC](https://www.evolver.bio/t/pump-and-light-gui-parameter-questions/254/1 "2021-01-20T22:21:16Z")

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A few questions on the GUI:

1. What does IN 2 do on the peristaltic pump array parameter? When I run the pump with it selected I get the following & nothing happens:  
 ![image](https://canada1.discourse-cdn.com/flex035/uploads/evolver/original/1X/738de9356f2cd6ebf846e44e7e426dec1cde8507.png)
2. What are the options A and B under the light parameters? ![image](https://canada1.discourse-cdn.com/flex035/uploads/evolver/original/1X/660651ab72b4bd3653283ba35774729a22381f54.png)

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### Author: ![bgwong](https://yyz1.discourse-cdn.com/flex035/user_avatar/www.evolver.bio/bgwong/32/262_2.png) [@bgwong](https://www.evolver.bio/u/bgwong)
#### Post date: [January 21, 2021, 4:25am UTC](https://www.evolver.bio/t/pump-and-light-gui-parameter-questions/254/2 "2021-01-21T04:25:07Z")

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Those only work if you have the other modifications to the system, like adding LEDs for optogenetics or adding a 3rd pump array for morbidostat applications. If you don’t have your system modded to do this, it won’t do anything.