How to perform a loopback test to test a serial communication system using Tera Term, With or without a Lantronix box
![OPUS devices update manual > Additional information > Manual update of the boot loader and service ramdisk (OS 1.x) > Manual update of the boot loader OPUS devices update manual > Additional information > Manual update of the boot loader and service ramdisk (OS 1.x) > Manual update of the boot loader](https://opus-update.topcon.com/projektor/2021/online_manual/opus_devices_update_manual_v1.8_img11.png)
OPUS devices update manual > Additional information > Manual update of the boot loader and service ramdisk (OS 1.x) > Manual update of the boot loader
![OPUS devices update manual > Additional information > Manual update of the boot loader and service ramdisk (OS 1.x) > Manual update of the boot loader OPUS devices update manual > Additional information > Manual update of the boot loader and service ramdisk (OS 1.x) > Manual update of the boot loader](https://opus-update.topcon.com/projektor/2021/online_manual/opus_devices_update_manual_v1.8_img12.png)