# HDLC Link management ... (SABM & UA) ???

**URL:** https://forums.digi.com/t/hdlc-link-management-sabm-ua/13175
**Category:** Rabbit
**Tags:** hdlc, ua, sabm
**Created:** [June 20, 2014, 5:33am UTC](https://forums.digi.com/t/hdlc-link-management-sabm-ua/13175 "2014-06-20T05:33:46Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![hcyoo](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@hcyoo](https://forums.digi.com/u/hcyoo)
#### Post date: [June 20, 2014, 5:33am UTC](https://forums.digi.com/t/hdlc-link-management-sabm-ua/13175/1 "2014-06-20T05:33:46Z")

</div>

i use RCM6700 for HDLC. (Serial F)

between two rabbit module, hdlc working very well.

but .between rabbit and another hdlc device,

occur problem.

the problem occur in the following flow.

1. another hdlc device send SABM message to rabbit.

2. rabbit send UA message to another hdlc device.

as above… after sending the UA message …

rabbit do not receive any data.

so… check rx\_data pin using oscilloscope.

rx\_data signal moves.

What is the problem ???

I would not know how to debug. ㅜㅜ