Recent upgrades of longitudinal diagnostics at FLASH

In the framework of the recent FLASH2020+ upgrade program, the longitudinal electron beam diagnostics of the FLASH accelerator had been modernized and extended by additional devices, including an electro-optical bunch length detector (EOD[1]), as well as an additional bunch compression monitor (BCM [2]) and a bunch arrival-time monitor (BAM [3]) in the new direct seeding beamline FLASH1. Also, the THz intensity spectrometer (CRISP [4]) received a modernized control interface that will allow non-experts to perform bunch profile measurements. The paper presents an overview on the current status of the longitudinal electron beam diagnostics at FLASH and the ongoing (re-)commissioning.