By James Floyd and Cole Downing, Logic Supply, Inc .
Is the devil you know better than the devil you don’t? Control systems professionals regularly face a version of this question when automation PCs are presented as part of the larger system package. Because it’s bundled in, you can have a high confidence that this PC works with the software and other components -- but you also know you may be paying $5000 for a slightly more rugged version of your Dell desktop.
Given the need to cut costs, many control engineers choose to “go rogue”. They select their own automation computers, either at the start of a project or when the existing units fail and they need replacements. If done right, this strategy gets you more value for less money. If done wrong, the initial sweetness of the lower sticker price sours as you spend time and money on integration issues.
Here are 6 things you need to ask your vendor to (a) assess whether independent PC selection makes sense and (b) to configure a unit that will meet your needs.
1. Most importantly, will the PC support the software -- and the connected devices?
It isn’t difficult to find a Windows or Linux compatible computer, the challenge is application compatibility. Software might be available on one platform but not the others. Device drivers may be out of date or simply not exist for other connected machines such as sensors, display panels, and robotic arms. Unfortunately, only so much can be done on paper and you may need a test unit in house to confirm compatibility.
2. Will the PC physically connect to the larger system?
If you have determined that the unit will support the connected devices, you need to make sure that the unit physically connects to the machinery, panels, and peripherals in the larger system. Don’t immediately look to the back panel I/O. Smart system configurations can meet I/O needs with onboard header pins and daughtercards.
Instead determine the type (USB 2.0, USB 3.0, COM, LAN, eSATA, DisplayPort, FireWire, S/PDIF, S-Video, TV-out/RCA, TPM, watchdog timer or what have you), total quantity, and relevant speed of the ports you need.
LGX AG150 - Low profile, fanless, industrial computer for a wide variety of embedded applications
3. What are your performance needs?
Assessing your performance needs is a great way to be proactive. Do you have a current platform to use as a point of reference? Does the software you are using have a minimum hardware spec? If not, how graphically intensive is your application? These questions inform CPU, GPU, and single vs. dual vs. quad core choices and more.
Obviously you need more CPU horsepower for an intensive application, but many people don’t think in the opposite way: For a basic, undemanding application, resist the urge to “throw hardware at your problem .” Senior hardware engineers agree over specifying performance requirements is the most common hardware configuration mistake. If, for instance, you need a system for order-flow management, or running data acquisition software, you aren’t going to need the latest and greatest high-graphics-performance CPU. But if you’re running an intensive machine vision application, high performance capacity is essential.
The bottom line is determining the minimum hardware requirements for your software. Be sure about what it is you need, and don’t pay for something you don’t.
4. What environment (including power environment) will your unit operate in?
Environment is going to be a major driver in your choice of hardware. Will the system be in a dusty environment? Will it be subject to shock or vibration? Can you describe the ambient temperature? Is there a space constraint? Mounting requirements? What power is available (e.g.110, 220, AC, DC, etc.)?
These environmental considerations drive case, motherboard, power supply, and storage choices. In a highly dust- or vibration-prone environment, a fanless chassis is essential. For instance, a tire manufacturer like Bridgestone needs a system that’s well-protected from the debris on the manufacturing floor. But frankly, regardless of the environment, eliminating moving parts will only help you. Even if you’re running the system in an ultra-clean and air-conditioned building, a fan can still drag in dust and harmful debris, and a moving hard drive can still malfunction.
Solid-state, fanless systems are more reliable in the long run, hands down. Hardware engineers always recommend eliminating moving parts if you can afford it.
LGX ML251 - Fanless Mini-ITX case with integrated LCD display and excellent thermal management
LGX ML251 - The Back Side
5. What are your storage and memory requirements?
Based on the environmental considerations above, decide whether a solid state or hard disk storage is more appropriate. But like we said above, SSDs are the way to go if you have the budget. In addition to removing a moving part, SSDs can also offer power loss protection, which protects against any data loss in unexpected power outages.This is something Logic Supply customers have found to be extremely useful.
Beyond the HDD vs. SSD choice, how much storage capacity do you need? What are your storage performance requirements (5400 RPM, 7200 RPM, transfer speeds)? Do you have any special storage considerations (RAID, multiple drives, boot devices vs mass storage)? What are your RAM capacity requirements?
6. What are your business/lifecycle requirements?
Cost is often a concern, but remember to think in terms of the lifecycle. These are typically < 3 years, 3-7 years, 7+ years. Lifecycle needs will determine whether you need particular motherboards and whether you need to look at revision control. Also consider also your physical requirements, how often they change and how that affects cost. For example, if you are building a sheet metal enclosure, you don’t want frequent revisions on the I/O.
When it comes down to price, you will definitely want to know what price per unit you need to hit, but stay flexible and think about external factors like “What is the cost of downtime or remote servicing?”
These question should help you drive reliability needs, inform Total Cost of Ownership calculations, and help you pick the right industrial automation computer for your needs.
