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Posts from — July 2007

Making an Interface PCB II – Parts and Resources

Updated 1/23/2008 with AMP socket connector part numbers (which some people find easier to hand assemble than 3M, but they are more expensive), and a bit more on MCAD.

Update 4/6/2011: Alibre Design Express hasn’t been available for years, and since Alibre Design Personal Edition isn’t suitable for PCB modeling, your low cost (<$500) MCAD options are limited.  Check out my Affordable MCAD post for some current choices that might work (depending on your needs).

A list of the parts and resources needed for the FP-SMC-1 Interface PCB. The Phoenix parts are available from a number of sources, including Digikey, but Mouser (who I will use) and Online Components sell them in small quantities.

Software:

  1. Eagle PCB. I’ll be using the Light version (free for non-commercial, $49 for commercial).
  2. Viewmate from PentaLogix, which is a free Gerber viewer.
  3. Alibre Design Xpress which will help check the mechanical side of the PCB (free). If time allows, I’ll cover other options for checking the mechanical fit of the PCB.

Board Houses:

  1. Sierra Proto Express
  2. Possibly SparkFun/BatchPCB (can be cheaper for 1 PCB)

Bill of Material for circuit board (excluding PCB):

  1. 4 Pin Header 10 pin (2×5) AMP 5102321-1
  2. 1 Pin Header 26 pin (2×13) AMP 5102321-6
  3. 15 Phoenix ZFK3DS 1,5-5,08 Terminal Block (Part Number 1704415)
  4. 1 Phoenix ZFK3DSA 1,5-6,08 (click on Additional Products) End Terminal Block (Part Number 1704554)
  5. 3 Phoenix ZFKDS 1,5-W-5,08 Terminal Block (Part Number 1706714)
  6. 1 Phoenix ZFKDSA 1,5-W-7,62 (click on Additional Products) End Terminal Block (Part Number 1706730)
  7. 2 Phoenix UMK-FE DIN rail feet (Part Number 2970031)
  8. 2 Phoenix UMK-SE 11,25 side elements (Part Number 2970002)
  9. 2 Phoenix UMK-BE 45 base (Part Number 2970015)

Bill of Material for cables:

  1. 8 IDC Socket Connectors 10 pin (2×5) 3M 89110-0101 or AMP 1658621-1
  2. 8 Strain Reliefs 3M 3448-89110 or AMP 499252-5
  3. 2 IDC Socket Connectors 26 pin (2×13) 3M 89126-0101 or AMP 1658621-6
  4. 2 Strain Reliefs 3M 3448-89126 or AMP 499252-3
  5. Ribbon cable 26 conductor AWG 26/28 0.050″ pitch (available from 3M and others, length depending on your need)
  6. Ribbon cable 10 conductor AWG 26/28 (available from 3M and others, length depending on your need)

Tony

July 26, 2007   1 Comment

The purpose of Test Driven Development

I was going through an old stack of JDJ‘s (Java Developer Journals), and saw an interesting commentary on Test Drive Development (TDD). The author said its purpose was to help you write the minimal amount of code necessary to meet the current requirements, and that having a test suite available was a nice side affect. His TDD development sequence is:

  1. Write tests that show your requirements, based on the perfect client interface
  2. Write just enough code to compile successfully
  3. Write just enough so that all the tests pass
  4. Refactor

Now apply this idea to the world of factory automation software. Hmm, could be interesting, but it wouldn’t work with PLC’s (rllUnit anyone? I don’t want to even imagine porting xUnit to IEC61131.)

Tony

July 21, 2007   No Comments

Kudos to Panasonic

Update 5/14/2008 – Bad Panasonic! It looks like they’ve removed the list prices.  You can still get online pricing (from OnlineComponents and Allied Electronics), but it’s still stupid to remove the price list.  It was handy as a quick guide to what’s available and what it roughly costs (online searches aren’t as convenient).  By the way, local distributor pricing is often better than national catalog pricing.

I was looking at Panasonic Electric Works America’s website recently, and noticed that they now have links for suggested list price for most of their products; for example, FP Sigma PLC pricing. Note that actual prices through a distributor will typical be at least 10-20% less.

I like to have list prices, because I need to have an idea of what stuff will cost. I’m not concerned about every dollar, but it makes a big difference if a PLC is $500 or $3,000.

Tony

July 20, 2007   2 Comments

Making An Interface PCB I – Introduction

This series describes how to have a PCB made for factory equipment from start to finish using a real board. I am not going to concentrate on the details of the PCB layout software (there are plenty of tutorials available for that), but instead cover details such as getting the right output out of the PCB layout software.

I am going to design a PCB that could be useful in a machine, using components I like. You should be able to learn from this example to design your own low cost board. The PCB will be designed to interface a Panasonic FP0 or FP Sigma PLC to a SMC pneumatic manifold. I am naming the board FP-SMC-1.
The board interfaces 16 PLC outputs to a SMC 26-pin header manifold. SMC uses this design on various manifolds that can have up to 12 stations, and each station can use 1 (for single acting) or 2 (for double acting) outputs. In my board, I use up to 8 stations; all of them can be single or double acting.

The board interfaces 16 PLC inputs to terminal blocks, so you can have two limit sensors (extended, retracted) for each pneumatic cylinder.

The board has a four power terminals, two +24V and two GND. Providing extra 24V and Ground connections allows the board to power another board.

The board mounts on a Phoenix UMK DIN-rail holder. I have successfully used the UMK series before. Phoenix also provides 3-D models, which is useful.

I will be using Eagle PCB to create the schematic and layout the PCB. I will be using Sierra Proto Express as the board house. I plan on investigating the creation of a 3-D board model.

Tony

July 9, 2007   No Comments