Q: imac hang wakup

Hello,

I'm not sure if that was the best title for this.  Perhaps explaining will offer more.

On my iMac 27" (late 2013) running latest Yosemite this happens from time to time (not a lot but enough to be irritating):

Actually, before I do that, some background/how I notice this:

I have a weather station connected via USB to my mac. It's constantly sending data to the app. I also have a web page to access the data.  There are times when I happen to check my website and no updates for a few hours.  Sometimes this just means internet is down or perhaps the app crashed.  I use Teamviewer to connect and fix if i can.  However, when my issue occurs, the iMac shows offline so I can't connect.

When I'm home I try to press any key or move mouse to wake up but it does not.  Sometimes there is a big delay while other times I have to tap the power button to wake up.  Once awake I need to restore the data from the app via Time Machine and then restart.  I also notice the last TM backup is always before the "hang" and none afterwards.

I have run digs with Apple on the phone, nothing. I had them look around, nothing big.  They hinted it could be a USB issue.

Here is what I have running with periperals installed:

iMac running Yosemite with latest updates

USB ports have:

1) UPS backup unit

2) Weather Station itself (via serial to usb cable converter)

3) Iphone lightning cable connected for when I want to backup phone

I also have a WD MyCloud NAS connected via Time Capsule

I experienced this yesterday and when I got home looked on console.  At the time around the "hang" I saw a bunch of messages:

Aug 26 06:48:13 --- last message repeated 1 time ---

Aug 26 06:48:13 Pauls-iMac.local SystemUIServer[317]: Menu Extra: <DisplaysExtra: 0x7f9b6b326bd0> is over retained.

Aug 26 06:48:14 Pauls-iMac kernel[0]: PM response took 2987 ms (54, powerd)

Aug 26 06:48:14 Pauls-iMac kernel[0]: [0x14d6242000, 0x3000]

Aug 26 06:48:14 Pauls-iMac kernel[0]: [0x3e7425000, 0x40000]

Aug 26 06:48:14 Pauls-iMac kernel[0]: [0x3e7505000, 0x20000]

Aug 26 06:48:14 Pauls-iMac kernel[0]: [0x3e7685000, 0x40000]

Aug 26 06:48:14 Pauls-iMac kernel[0]: [0x3e74a5000, 0x20000]

Aug 26 06:48:14 Pauls-iMac kernel[0]: [0x3e76c5000, 0x40000]

Aug 26 06:48:14 Pauls-iMac kernel[0]: [0x3e7525000, 0x20000]

Aug 26 06:48:14 Pauls-iMac kernel[0]: [0x3e7465000, 0x40000]

Aug 26 06:48:14 Pauls-iMac kernel[0]: [0x3e74c5000, 0x40000]

Aug 26 06:48:14 Pauls-iMac kernel[0]: [0x3e7645000, 0x40000]

Aug 26 06:48:14 Pauls-iMac kernel[0]: [0x3e7845000, 0x20000]

Aug 26 06:48:14 Pauls-iMac kernel[0]: [0x3e7805000, 0x20000]

Many more of these Kernel messages then I get:

Aug 26 06:48:14 Pauls-iMac kernel[0]: *** kernel exceeded 500 log message per second limit  -  remaining messages this second discarded ***

Aug 26 06:48:15 Pauls-iMac kernel[0]: ARPT: 1768229.989308: wl0: leaveModulePoweredForOffloads: Wi-Fi will turn off.

Aug 26 06:48:15 Pauls-iMac kernel[0]: AppleThunderboltNHIType2::prePCIWake - power up complete - took 2 us

Aug 26 06:48:15 Pauls-iMac kernel[0]: AppleThunderboltGenericHAL::earlyWake - complete - took 0 milliseconds

Aug 26 06:48:15 Pauls-iMac kernel[0]: IOThunderboltSwitch<0xffffff8024242200>(0x0)::listenerCallback - Thunderbolt HPD packet for route = 0x0 port = 11 unplug = 0

Aug 26 06:48:15 Pauls-iMac kernel[0]: IOThunderboltSwitch<0xffffff8024242200>(0x0)::listenerCallback - Thunderbolt HPD packet for route = 0x0 port = 12 unplug = 0

I have nothing plugged in nor do I use the thunderbolt port.

I checked my energy settings in preferences:

Turn display off after is set to 1 hour

The only check mark is: Prevent computer from sleeping automatically when the display is off

Any thoughts on what this could be and/or how to troubleshoot and/or what to say to Apple (should I call in again)?  If there is any info I left out or anyone needs, just let me know.

Thanks,

Paul