# SLC connection issue: Disconnected, determining protocol

**URL:** <https://forum.inductiveautomation.com/t/slc-connection-issue-disconnected-determining-protocol/10096>\
**Category:** Ignition\
**Created:** [June 5, 2015, 5:40pm UTC](https://forum.inductiveautomation.com/t/slc-connection-issue-disconnected-determining-protocol/10096 "2015-06-05T17:40:49Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![CA\_HMIDev](https://avatars.discourse-cdn.com/v4/letter/c/cc9497/32.png) [@CA\_HMIDev](https://forum.inductiveautomation.com/u/CA_HMIDev)\
**Post date:** [June 5, 2015, 5:40pm UTC](https://forum.inductiveautomation.com/t/slc-connection-issue-disconnected-determining-protocol/10096/1 "2015-06-05T17:40:49Z")

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Hello. I have a server on site attempting to connect to a SLC 5/05 PLC. Unfortunately, the connection is never established. The device status is listed as ‘Disconnected: Determining Protocol’. I’ve attached a log. The odd thing is that I was able to connect from a different server a while back, and the connection has been maintained since (with 2738 subscriptions). It is new connections that cannot be established. I’ve tried changing the poll rate to no avail. Is there anything else that I can do? Any help would be greatly appreciated. Thank you.

![](https://us1.discourse-cdn.com/inductiveautomation/original/3X/2/f/2f0984456f8dd47c5beb0a68b72c3d6cf62ef2aa.jpeg)  
[logs(1).bin.gz](https://us1.discourse-cdn.com/inductiveautomation/original/2X/2/295e966321a4104099fd789ebac4c3db6c9c7209.gz) (325 KB)

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**Author:** ![jim\_lapratt](https://avatars.discourse-cdn.com/v4/letter/j/cc9497/32.png) [@jim\_lapratt](https://forum.inductiveautomation.com/u/jim_lapratt)\
**Post date:** [June 5, 2015, 5:52pm UTC](https://forum.inductiveautomation.com/t/slc-connection-issue-disconnected-determining-protocol/10096/2 "2015-06-05T17:52:07Z")

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Check the gateway setting on the PLC

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<div class="post-metadata">

**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [June 5, 2015, 6:56pm UTC](https://forum.inductiveautomation.com/t/slc-connection-issue-disconnected-determining-protocol/10096/3 "2015-06-05T18:56:38Z")

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Also check for other HMIs or devices making connections. Many of the SLC 5/05 processors are only capable of supporting four (4) inbound TCP/IP links.