Monthly Archives: December 2011

NTSB Suggests Banning Use of Electronic Devices While Driving — Yeah?

Leave a reply

I was a bit surprised to see all the hubbub about the NTSB recommending banning the use of cell phones and other electronic devices while driving. You see, they already passed similar legislation here in Ontario, and the sky hasn’t fallen.

As someone who used to answer my cell phone while driving (I always justified to myself that I was always on a straight stretch of road or not in town but in truth I would answer it almost any time), I can honestly say I was wrong to do that, and I was converted by the evidence. Our brains just don’t seem to be wired to handle cell phone conversations while driving, even though we do much better with other tasks like talking to a passenger.

Unfortunately our brains are also poorly wired to understand statistics. The fact that I used cell phones while driving and I‘ve never had an accident because of it is apparently all the proof I needed to know that it was safe. Of course, the real research disagrees:

There are, of course, edge cases. I know that here you’re free to dial 911. Also, you’re not allowed to be manipulating a Navigation System, but I believe you’re still allowed to have one turned on giving directions (that’s pretty reasonable – you can set it before you leave, or let your passenger set it).

For those of you who like to let their spouse know when you’re almost home, I’ve heard they can get an app where they can see your location in real-time on their phone by tracking your phone’s GPS, so there’s no need to call. (Yeah, I think that’s creepy too, and maybe they already have it installed!)

Safe(r) Data Collection from a PLC

4 Replies

There’s been a lot of discussion recently about the dangers of connecting automation equipment to networks, and yet there are significant pressures to do so. Of course, I don’t ever think that you should take a PLC and put it on an internet accessible IP address, but it’s certainly common practice to connect industrial automation equipment to internal LANs to facilitate data collection. People in the front office need to push production planning information down to the production floor, and they need real-time data on what’s going on (not to mention for historical data logging, historians, etc.).

It’s all too common to throw a PLC on the same network as your front office, and I’ve seen it blow up. What happens is something invariably goes wrong on the office network (someone plugs two ports together on the switch in the boardroom, or someone brings in an infected music player and plugs it in, or the DNS server at head-office goes down and the local DNS doesn’t work correctly… I’ve seen a lot). However, you want your machines to keep going when this happens.

This is all made worse now that (a) industrial automation equipment is more commonly based on off-the-shelf commodity hardware and software (e.g. windows PCs) and (b) the people writing malware can actually spell PLC now. Up to this point there’s been some form of security through obscurity.

If you have a local IT staff that’s on the ball, you really should be getting them to handle the network layout. On the other hand, if you’re in a small facility with limited resources, there’s a lot you can do by making some simple design choices that will go a long way towards improving the reliability and security of your systems.

Most automation cells now come with an Ethernet switch already built-in. Typically this is an industrial spec. DIN-rail mounted one. It’s not fancy, but it’s supposed to survive in a panel. These Ethernet switches are there to connect your PLC to your HMI, and increasingly to connect your PLC to Ethernet-based I/O like Ethernet/IP, etc. The common (and wrong) thing to do is to drop a network cable from your plant network to your panel and plug it right into this Ethernet switch. This creates some technical problems right off the bat:

The automation devices typically have fixed IP addresses (I personally prefer this because it means these devices aren’t dependent upon an external DNS or DHCP server – two less dependencies are good). Chances are that these IP addresses won’t work on your plant network, so you have to manage those IPs at the plant level. You’re opening yourself up to someone with the wrong IP on their laptop pouncing on your PLC’s IP address, and then bam, your machine is down.

A much better way is to place some kind of Router with NAT between the plant network and the machine’s Ethernet Switch:

Now if you’re just a little manufacturer with two machines out back and your data-collection link isn’t critical, you can probably get away with one of those home routers from Best Buy that you’d use to connect your laptop and your desktop at home to your cable modem. Note that it doesn’t need to be wireless, and you’re probably better off if it isn’t. The way you hook it up is to connect the Internet (Uplink) port on the router to the plant network and run a cable from one of the ports on the LAN side to the existing Ethernet switch in the machine. If your data needs to be a bit more reliable, consider buying some kind of Cisco router with NAT capability (but you’ll be going from the $50 range to many hundreds of dollars – your choice).

Now, when you configure it, you want to make sure that you turn off the port forwarding function, the DMZ function, disallow remote administration, and block all anonymous internet traffic (these should be default settings, but it’s good to check). Also, make sure the router’s local IP address doesn’t conflict with the PLC’s and HMI’s, and make sure they have the same subnet. Typically you’ll want to either turn off DHCP on the local side, or limit it to a range that won’t conflict with the fixed IPs. DHCP is handy when you connect your laptop to the programming port. Now what you’ve done is made it somewhat invisible from the plant side. Some piece of malware scanning for devices on your plant network should just see a black hole.

Now on the PLC side, you can now initiate a connection to the data collection server even though the data collection server can’t connect to the PLC (in the same way that your home computer can connect to Google, but Google can’t get to your PC – theoretically). Note that a piece of malware on your data collection server or on one of the routers/switches in your plant network could intercept this communication, and own your PLC, but at least you’ve significantly reduced the surface area of attack. Not perfect, but reasonable at this time, depending on the sensitivity of your equipment. I’m assuming you’re not enriching uranium or providing drinking water to my community.

(I’m going to be talking specifically about Allen-Bradley products now – sorry.)

So how do you get the data from the PLC to the data collection server? In the old days you’d have some software on the server like RSSQL, and it used a product like RSLinx Enterprise and as far as I know, it initiated the connection to the PLC. That won’t work in this case. Sometimes you’d throw an OPC server in there, and have some kind of historian that would log tags to a database. That OPC server, obviously, needs to be able to initiate a connection to the PLC. To use a router with NAT, you’d need to port-forward from the router to the PLC (or to the OPC server if it was inside the machine network). That’s undoing a lot of our protection.

What you need to do is initiate the connection from the PLC, and have the Data Collection computer act as a Server. One way to do this is with a 3rd party Ethernet card, like this MVI56-GEC card from Prosoft for the ControlLogix line. I have used that in the past to connect to a server, but it involves a lot of ugly PLC coding. It’s your only option if you have to conform to someone else’s protocol though.

If you just want to write data directly into a SQL database, there are 3rd party products that will let you do this (basically a SQL Server connector card).

But there is an option without buying any new hardware. The ControlLogix/CompactLogix lines can send Unsolicited CIP messages, and you can find products that can receive these messages in the PC world, like CimQuest’s NET.LOGIX product. It can act as a server and receive data directly from the PLC – either individual tags, or even arrays of UDTs. The code on both ends is relatively simple, so all you have to pay for is the NET.LOGIX runtime license, which is cheaper than the hardware alternatives. Note that you can also do this with PLC5 and SLC500 devices, though there’s some more effort involved.

I hope that’s enlightening. This is by no means a perfect solution, but it’s reasonable for now. It doesn’t plug the laptop hole (the programming laptop is probably still your #1 vector for malware to get into your machine network). It’s susceptible to man-in-the-middle attacks between the router and the data collection server. It’s susceptible to exploitable bugs in the router’s firmware. Beware and use your own judgement.

Decision-making in Organizations

Leave a reply

I think I can group decisions into two types:

  1. Decisions where it’s really important that we make the right decision
  2. Decisions where it’s really important that we make any decision and everyone gets behind it

For instance, deciding what products to launch for the Christmas season is really important. The choices made will have a profound impact on the bottom line of your company. On the other hand, it didn’t really matter what side of the road we decided to drive on, but it was really important that we, as a group, made a decision, and everyone agreed to it.

Now let’s talk about how organizations make decisions. I think there are typically two approaches:

  1. Appeal to authority
  2. Appeal to committee

When appealing to authority, the accounting department has the authority to make cash-flow decisions, and the engineering department has the authority to make technical decisions, and the marketing department gets to decide whether we run Superbowl ads or Craigslist ads. The CEO can override these decisions when a higher level view recognizes a different need.

When we appeal to committee, we gather all the “stakeholders” who then sit around a table, generally as equal representatives of their respective departments, and come to some kind of consensus.

I don’t think anyone’s surprised by the fact that when it comes to making decisions where being right is the most important criteria, authoritative decisions tend to be better than committee decisions. In the same way, when success of the decision is tied to consensus rather than the “correctness” of the decision, then committee decisions probably have an edge.

Now, if you’ve spent any time around government offices, you’ll realize that almost all decisions, including planning the staff Christmas gathering, are done by committee. Very large publicly traded companies don’t seem to be much different. On the other side of the spectrum, small companies don’t need much consensus because they’re small, and they tend towards decisions based on authority. Successful entrepreneurs seem to surround themselves with knowledgeable people and trust those people to make intelligent choices. This makes them well suited to make decisions where it’s important to be right, like how much raw material to buy this month, and where to commit other scarce resources.

It’s interesting to look at the outliers too. Apple is famous for being the exception that proves the rule. Despite being a huge organization, all information seems to indicate that Jobs ruled it with authority, not committee. And since he seemed to make good decisions, they were successful. Apple shareholders beware.

Now let’s go all 7-Habits on this and put it in quadrants, dividing decisions along two axes:

Great Risk
if Wrong		 Little Risk
if Wrong
Must have
everyone’s
support		 1:
Invade Iraq?
What product
for Christmas?		 2:
Drive on the
Left or Right?
Don’t need
everyone’s
support		 3:
Bail out
the banks?
Windows or
Linux servers?		 4:
Chicken or Fish?
Bike-shed color?

I divided it into four quadrants numbered 1, 2, 3, and 4. Quadrants 2 and 3 we’ve already covered. In quadrant 2, committees really shine, and in quadrant 3 authority really shines. I’m not even going to talk about quadrant 4.

Quadrant 1 is the tricky one. The Easter Island society collapsed because they were faced with a decision: do we allow everyone to cut down all the trees, or do we centrally manage it? Obviously they made the wrong decision, but the right decision would have required broad support, which is why it’s so difficult.

Apple beat the quadrant 1 decisions by rolling both authority and consensus into one charismatic (and knowledgeable) leader. People follow leaders who have a track record of delivering on their promises. Success is a positive spiral.

The idea that you can take committees and make them authoritative is misguided. On the other hand, we’ve seen our share of authority figures who’ve succeeded at the long road of building consensus around the right decisions. They are our political and cultural heroes.

All of this brings me to two conclusions:

First, unsurprisingly, is that we shouldn’t put big government bureaucracy in charge of quadrant 1 type decisions (and that’s a bit scary, because they certainly are in charge of those decisions now).

Second is that our system of government tends to promote leaders who are good consensus builders without promoting leaders who are likely to make the right decisions. I’m not saying it promotes leaders who are likely to make bad decisions; I’m just saying it’s neutral on the issue.

I’m not out to change the system of government, but I think a two-pronged offensive could make a dent: on one side our domain experts tend to live in a world where consensus building doesn’t matter because their community has the skill to recognize logical consistent arguments. Scientists simply publish their findings and wait for others to confirm or disprove them. Engineers test various design alternatives and measure their performance. Unfortunately this means our domain experts lack the soft skills necessary to convince us to do the right things. A marketing budget for these experts, perhaps paid for by some rational-minded philanthropists, could go a long way.

On the other side, the general public is hopelessly lacking in critical thinking skills. We live in a world where logic is first introduced as a university-level introductory philosophy class. It belongs in high school (along with some other suspiciously missing life-skills like food/nutrition and childcare).

Unfortunately the high school curriculum is decided on by… a committee.