# Laser Lock Box (LLB) Configuration

**URL:** <https://forum.liquidinstruments.com/t/laser-lock-box-llb-configuration/1016>\
**Category:** Software & APIs\
**Created:** [August 15, 2024, 6:30pm UTC](https://forum.liquidinstruments.com/t/laser-lock-box-llb-configuration/1016 "2024-08-15T18:30:19Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![T\_Hinds](https://avatars.discourse-cdn.com/v4/letter/t/e19adc/32.png) [@T\_Hinds](https://forum.liquidinstruments.com/u/T_Hinds)\
**Post date:** [August 15, 2024, 6:30pm UTC](https://forum.liquidinstruments.com/t/laser-lock-box-llb-configuration/1016/1 "2024-08-15T18:30:19Z")

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Hello,

I am attempting to configure a LLB instrument in Multi-instrument Mode using the Matlab API. I would like to tune the slow controller using the same line from the example in the documentation ([Examples for MATLAB | Moku API](https://apis.liquidinstruments.com/examples/matlab/#laser-lock-box)), for the llb object:

llb.set\_pid\_by\_frequency(2,-10,‘int\_crossover’,50);

However, a “method is not supported in the current context” error in the Request/http\_post appears. Issuing “disp(llb.summary());” confirms the slow controller is not set to the parameters I specify. I also encounter the same error when trying to set the LLB slow controller as its own instrument, outside Multi-instrument mode using the Matlab API running the entirety of the referenced example. How can I set the slow controller using the Matlab API? I would also like to control whether or not the slow controller output is on or off, so OutputB can output a scan, modulation, and offset with/without the slow feedback signal. Is this switch, visible in the moku LLB instrument GUI, controllable with the Matlab API?

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**Author:** ![hanklong](https://yyz1.discourse-cdn.com/flex035/user_avatar/forum.liquidinstruments.com/hanklong/32/288_2.png) [@hanklong](https://forum.liquidinstruments.com/u/hanklong)\
**Post date:** [August 15, 2024, 10:47pm UTC](https://forum.liquidinstruments.com/t/laser-lock-box-llb-configuration/1016/2 "2024-08-15T22:47:05Z")

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Hi @T_Hinds Thomas,

I am sorry for the issue you are experiencing. We are aware of this issue and we are working on this actively. Thank you very much for your understanding and patience!

For turning the PID control signal off, you can use `set_output` to configure the control output signal connections. [Moku API](https://apis.liquidinstruments.com/reference/llb/set_output.html)

Thank you,  
Hank

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**Author:** ![T\_Hinds](https://avatars.discourse-cdn.com/v4/letter/t/e19adc/32.png) [@T\_Hinds](https://forum.liquidinstruments.com/u/T_Hinds)\
**Post date:** [August 16, 2024, 4:02am UTC](https://forum.liquidinstruments.com/t/laser-lock-box-llb-configuration/1016/3 "2024-08-16T04:02:52Z")

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Thanks Hank, I verified the first boolean argument in the line “llb.set\_output(2,true,true);” enables/disables the slow control signal, and the second controls Output B. Looking forward to updates on the slow controller tuning.