Alverson, S.C. Gill, D.K. Saraf, S. JACoW Publishing Geneva, Switzerland 2226-0358 978-3-95450-238-7 10.18429/JACoW-ICALEPCS2023-THPDP086 English 1551-1555 controls PLC cryomodule vacuum operation Contribution to a conference proceedings 2024 2024-02 https://doi.org/10.18429/JACoW-ICALEPCS2023-THPDP086 https://jacow.org/icalepcs2023/papers/thpdp086.pdf The LCLS-II Project at SLAC National Accelerator is a major upgrade to the lab’s Free Electron Laser (FEL) facility adding a new injector and superconducting linac. In order to support this new linac, a vacuum pumping scheme was needed to isolate the liquid helium lines cooling the RF cavities inside the cryomodules from outside ambient heat as well as to exhaust any leaking helium gas. Carts were built with support for both roughing and high vacuum pumps and read back diagnostics. Additionally, a Programmable Logic Controller (PLC) was then configured to automate the pump down sequence and provide interlocks in the case of a vacuum burst. The design was made modular such that it can be manually relocated easily to other sections of the linac if needed depending on vacuum conditions.