How can I change the end device parameters then if the link is down most of the time?

I would recommend starting by increasing the wake time and decreasing the sleep time via remote AT commands.

But I’m unable to make connection long enough to make connection to endpoint to change its parameters. I’m using some random zigbee pro smoke detector for learning/testing and it refuses to connect to the network (as the led is still blinking once per second, which by the detectors manual should mean that it hasn’t made any connection to its gateway, although XCTU sees the device time to time).
Or are those changes made in coordinator?

If you are using a 3rd party device, then the XBee has no way to change the settings of that 3rd party device.

Are you sure that device is not a home automation device? If it is, you have to use special settings for the association to occur. You may even need to add or write an application that sends specific ZDO commands to get it to remain connected.

It is home automation device.
https://www.develcoproducts.com/products/sensors-and-alarms/smoke-sensor-classic/
unfortunatelly it doesn’t have any technical manual.
Some sister model has some, but i’m unsure how similar they are:https://www.develcoproducts.com/media/2746/smszb-120-technical-manual-smoke-alarm.pdf

May I suggest you look over http://knowledge.digi.com/articles/Knowledge_Base_Article/Zigbee-Home-Automation/?q=Home+automation&l=en_US&fs=Search&pn=1

You are most likely going to need to contact the manufacture of that device to find out if there are any additional requirements needed for association to occur.

Thank you for the quide. I tried to apply the following settings:
ZS 2
AP 1
AO 3
EE 1
EO 2
KY 0x5A6967426565416C6C69616E63653039
but still no luck controlling the end devices.

Did you check with the vendor of the other device to find out what commands or responses they need to finish association?

Hello,

I would like to return back to this old topic.
Vendor (Develco) is not willing to answer questions as they are P2P company only. The partner who should support customers is bankrupted. Any hints who I should extend HA end devices wake time by ZDO ?

Standard ZigBee devices don’t implement the XBee AT command set and aren’t configurable via X-CTU. Doesn’t matter if they have a longer/shorter sleep time.

To communicate with the smoke sensor in a meaningful fashion you need to communicate over the ZDO (basic network discovery and control common to all devices) and the ZCL (application specific functionality like temperature for thermostats, etc).

If you’re trying to learn HA I wouldn’t recommend starting with a sleepy end device. Complicates just about everything even if not the issue in this case.

If you haven’t already, track down a copy of the core ZigBee and ZCL specifications from zigbee.org.

Digi does provide a library with some basics of ZDO/ZCL at https://github.com/digidotcom/xbee_ansic_library. Definitely needs extending/refinement for specific use cases. A ZigBee over-the-air sniffer is also very helpful.