ULPM is not working in AR7554 with legato version 16.01.8.m1



I am getting below error during Ultra Low Power Mode on legato version 16.01.8.m1.

Please find the below error logs:

Aug 23 12:03:59 swi-mdm9x15 user.emerg Legato: EMR |
powerManagerService[524]/powerMgr T=main | le_ulpm.c WriteToSysfs() 95 | Unable
open file /sys/module/swimcu_pm/boot_source/timer/timeout for writing
(No such file or directory). Wrong Boot-source or Firmware

Aug 23 12:03:59 swi-mdm9x15 user.emerg Legato: EMR |
Middleware[32171]/framework T=main | le_ulpm_client.c
le_ulpm_BootOnTimer() 519 | Valid response was not received from server

Please provide your inputs/suggestions on this topic.

Thanks & Regards,


Hi @RahulG,

It seems that pmtool is not supported on AR devices and is meant for WP modules such as the WP85xx.



Hi @CoRfr,

Thanks for the information.

Do you mean to say AR devices does not support Power management of Legato?
Is there any alternative way to control power management states on AR device.

Thanks & Regards,



We are completely blocked due to above issue in our ULPM development process on AR7 device.
Any kind of inputs/suggestions on this topic is highly appreciated.

Thanks in advance.



Hi @RahulG,

You will need to contact application engineers at Sierra Wireless to get support for this module.