Let me explain it this way: Because I'm worried about the reliability of the SD card, I'm not likely to prevent basic operation and general operation if it fails. There's going to be sufficient memory otherwise for the device to run and operate correctly.
The purpose of the additional memory is for various large data storage. An example would be if this hardware made it into a site monitor Base unit, being able to keep all of the firmware images for all of the expansion module types on the SD card. The unit would then pull from there (much faster) to upgrade expansion modules in a fraction of the time. Another example would be supporting email notifications for events - i.e. the temperature is too cold. Without that functionality, the enhanced features would not be available. More applicable to the current design, there's been some requests for on-device logging of enough data so that certain values would have historical graphs. And so on. This thread is definitely giving me a lot of things to think about... -forrest On Mon, May 18, 2015 at 8:40 PM, Ken Hohhof <[email protected]> wrote: > I would agree with George’s numbers. Some of our smaller enclosures > don’t have much thermal mass or internal heating. With the crazy weather > extremes, we could conceivably get down to –25F inside the box for a day, > especially the ones we purposely put on the north side of a grain bin to > shield them from the summer sun. > > My question would be, what happens if it gets that cold? Lose some data? > Lose the firmware? Permanently damage the device? I could live with some > data loss as a result of a record temperature day. But I wouldn’t want to > go out and replace a failed unit when it’s that cold. > > *From:* George Skorup <[email protected]> > *Sent:* Monday, May 18, 2015 9:32 PM > *To:* [email protected] > *Subject:* Re: [AFMUG] Enclosure low temperature > > This winter was pretty cold. For about a week straight in the middle of > January and again in February, I had a few base units reporting under 0F > every night. And I know the outside air temp was -20 to -25F. Obviously > take the base unit's temp reading with a grain of salt because it's clearly > generating some internal heat. I would bet inside the enclosures it was > easily -15F. But I think your -13F is probably OK. > > On 5/18/2015 9:09 PM, Forrest Christian (List Account) wrote: > > What is the lowest temperature that each of you would normally expect > to see in your enclosures? > > The reason I'm asking is that I'm in the process of developing up a few > new products. > > To date, all of the packetflux products are designed with components rated > -40 to +85C (I.E way cold to way hot). I'd like to retain this rating, > but I'm running into a minor snag: > > For storage, I'm planning on integrating a SD card (probably microSD) in a > socket. I only need a GB or so, and SD card memory is inexpensive at that > range. > > Unfortunately, all the reasonably priced SD cards are only rated down to > about -25C or -13F. which are about ~$3 in qty. "Industrial temperature > range" ones which are good down to -40C/F are available but they add at > least $30 to the cost for non-name brand, and even more for known brands. > When you're talking about a $100 end-user price, a $30 1GB SD card seems > excessive - and probably isn't even possible if I want to meet the $100 > price with some margin. > > So, I'm currently playing the 'what options do I have' game. I hate to > ship a product only rated down to -25C/-13F, but I know for at least a > large chunk of my customer base they never see below this temperature, > especially when you add a watt of power dissipation in the case with the > device. Which leads me back to my original question: What's the lowest > temperature most people would expect to see inside their enclosures. > > -- > *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.* > Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 > [email protected] | http://www.packetflux.com > <http://www.linkedin.com/in/fwchristian> > <http://facebook.com/packetflux> <http://twitter.com/@packetflux> > > > -- *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.* Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 [email protected] | http://www.packetflux.com <http://www.linkedin.com/in/fwchristian> <http://facebook.com/packetflux> <http://twitter.com/@packetflux>
