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New Micro PLCs Go In Different Directions

It’s interesting to compare and contrast new micro PLCs from Siemens (S7-1200) and Panasonic (FP0-R).  Both are compelling upgrades from the previous series (Siemens S7-200, Panasonic FP0), but while Siemens adds Ethernet connectivity, Panasonic adds a USB port.

The FP0-R series looks like a direct replacement for the FP0, but with more: more memory, faster instructions, faster counters, and faster pulse outputs.  The biggest upgrade is a USB port, which is very nice: no custom programming cable required!  Or save some money: I like to use PLCs with two comm ports, one for communicating with the PC, and one for debug.  With the added USB port, I can use a PLC with one serial port, saving about $30, and use the USB port for debug.

I hope Panasonic has improved the USB port speed; I’ve heard that the FPX series uses an internal serial/USB bridge, so the USB port is limited to a wimpy 115,200 bps.

The FP0-R still isn’t as capable as the FPG (FP Sigma) series, but since it’s the same price as the FP0, I’m already looking at changing over from the FP0 to the FP0-R.

The Siemens S7-1200 models appear similar to the previous S7-200 models, but with more: more memory, more analog (even the base models have analog inputs), faster instructions, faster counters, more expansion (using signal boards) and faster pulse outputs.

What’s wonderful?  Siemens added an Ethernet port with Profinet and standard TCP/IP capabilities.  Networked devices are so much more convenient and useful than PC-connected USB devices.  For example, Profinet should make it simple and inexpensive to create a peer to peer PLC network, in addition to high speed communications to HMIs.  You have to add expensive networking modules to create a Panasonic PLC network.

The S7-1200 CPUs include other goodies, such as room for extra boards on the base CPU (for extra comm ports or wimpy (2DI/2DO or 1AO) I/O boards), 1M flash memory for extra (non-program) storage, and a proprietary memory slot.

Unfortunately, Siemen’s STEP7 Basic software currently only includes Relay Ladder Logic and Function Block programming; Panasonic’s FPWinPro supports all five IEC61131 languages, including my favorite: Structured Text.

Like the previous S7-200 series, base models have limited expansion: no signal modules for the 1211, 2 for the 1212, and 7 for the 1214.

The Panasonic FP0-R PLCs are much smaller; the transistor output models use high density box header connectors , while Siemens provides screw terminals.  I much prefer the box headers, since I can easily make a cable to a custom PCB breakout board.  It’s hard to wire directly with screw terminals without additional terminal blocks (for extra power and ground, etc).

The Panasonic FPX series are more like the S7-1200, since they also use screw terminals and provide room for plug in modules.

Excluding communications (USB vs Ethernet), the S7-1200, FP0-R, and FP-X are all similar in capabilities and price (IIRC, S7-1214 DC/DC/DC, FP0R-C32CT, and FPX-C30TD are all about $280, while the FP0R-C32T is about $245).

Which will I use?  I’d love to try out the S7-1200, but for my current projects the FP0-R and FPG are a better fit, since they support Structured Text and use box header connectors.

The S7-1200 is pretty close to a no-brainer if you need Ethernet:  Panasonic’s Ethernet module (FPWeb2; ~$430) alone costs more than a S7-1214 CPU; Automation Direct’s Ethernet modules start at $175, and you still have to add the PLC CPU.

I plan to write about this in more detail: I think micro PLCs are a great alternative to PC I/O options such as PCI boards from Advantech or USB modules from Measurement Computing.  The PLC’s cost the same or less for 24V I/Os, and have the advantage of being programmable — it’s nice to have the PLC handle some I/O, while the PC handles the rest via serial, USB, or Ethernet communications to the PLC.

Final notes:

  • Panasonic has gone backwards by not listing prices and requiring registration to download PDFs.
  • If you’re interested in the S7-1200, talk to your local distributor to see if they have a package deal.  For example, in Silicon Valley, E&M periodically offers 1 day introductions with a nice deal on the S7-1211.

October 29, 2009   2 Comments

Making a Panasonic PLC Programming Cable

I’ve added a section on my wiki describing how to make a serial cable to connect to the Panasonic FP0 or FP Sigma Programming Port. Later I hope to update it with more pictures.


FPG Programming Cable

July 16, 2008   6 Comments

Limitations to the Personal Computer Model

I was looking at automation blogs and come across this comment about Beckhoff:

“Europe’s most successful PC pioneer, Hans Beckhoff, has a simple two-part formula for success: 1. Put everything in software, on one platform, and 2. Give the customer everything he needs so he doesn’t have to buy anything else.

Interesting, since Beckhoff makes its money selling hardware. But, its hardware is all PC connected.

A lot of people view copying the PC industry as the inevitable way forward for the automation industry. This means using PC industry standards, such as OPC (originally based on MS’s OLE technology), Windows XP and CE, Ethernet, PXI, and embedded PC’s.

The big advantage is the lower cost, and theoretically more standardization, but there are many disadvantages, such as:

  • The short lifespan of PC technology. A personal example – I have a PC at home with a good Quadro AGP video card. How many new AMD AM2 motherboards support AGP? 1, and it’s not very good. So building equipment designed to last 5 years or more with generic PC technology will have problems with spares down the road.
  • PC technology isn’t always so cheap. Sure, generic PC’s, even in a 4U rack mount case, are cheap. But if you need IP67, or fanless, or a PanelPC, or guaranteed spares – well, your performance goes down and your price goes up.
  • Innovation is shifting away from PC’s. If an automation company continues to be PC-centric, they will miss innovation based on the new innovation drivers, such as web standards (now much sexier than MS’s COM technology), cell phones, and automotive electronics.
  • Commodity OS’s aren’t real time. I know, I’ve tried to do very soft real time with Windows, and it wasn’t pretty. Linux looks like it’s slowly getting there for soft real time, but it’s not mainstream yet in the factory. Yes, there are add-ons, but they cost extra in money (e.g. Venturecom) or time (learning hard RT extensions for Linux)
  • PC standards often do not support industrial needs well, and thus need tweaking; for example, the PCI bus morphing into CompactPCI and PXI, and Ethernet being extended with EtherCAT. But the volume goes down, prices go up, and you lose some of what made PC technology compelling.
  • Too many standards – think of all the industrial Ethernet protocols.
  • Old technology does not go away, so PC automation control needs to be able to communicate with the rest of the world, including PLC’s.

A company can’t be everything to everybody, and Beckhoff is right to focus on PC-centric automation. But if I were running an automation component company, my formula would be “1. Give your customer products that help him build better machines and 2. Understand you cannot meet all of your customer’s needs – integrate easily with the rest of the world.”


June 8, 2007   No Comments