Paint Flow Control Project, Chapter 3.24, Some tasks completed and more work to do

Good progress but more to do. I showed a list of tasks in my last post and have an additional software task. Thomas wanted some changes to include a Manual mode along with the Automatic mode, the Manual mode to allow the operator to set the controller output irrespective of the measured flow, an open-loop mode. The Automatic mode would be the same as before, allowing the operator to set a flow rate for the paint flow. The Paint Gun ON/OFF would be eliminated since the paint gun has a bypass valve to allow the paint to continue flowing even when the gun is shut off. So this required some not inconsiderable changes in the GUI along with some software changes, but minimal software changes. Here's a photo of the new GUI showing the Manual settings along the top with the Automatic settings below:

The New GUI Screen with Manual and Automatic Modes.

On startup, the mode is Manual and initially I have set the output to the I/P converter for the pump control to 500, that's 500 ml/min assuming the pump output is linear with respect to the I/P converter signal. In retrospect, perhaps I should change the Manual control to a Percentage of maximum value. Anyhow, the operator can "click" on the screen at the MAN and AUTO "buttons" to switch modes and the current mode is shown at the far right in the STATUS label. When the paint system is ready for painting the operator can switch to Automatic mode and operate in Closed-Loop controlling the paint flow rate to the AUTO setpoint. In the photo above, the controller started in the MANUAL mode at the 500 setting and then I switched to AUTO mode wit the setpoint at 1000 ml/min.

In my last post, I showed a list of software and hardware tasks.
The software tasks were:

1. record data on a USB flash drive plugged into the BBB (completed).
2. add a Real Time Clock (RTC) module to the BBB (completed).
3. add software for the RTC (completed).
4. add an Idle mode to the paint flow control when the paint gun was turned off (deleted).

Then there are the hardware tasks: 

1. fabricate the Analog I/O boards and get them loaded (board fab completed).
2. design the hardware system, purchase power supplies and other parts (parts purchased), and
3. get the hardware installed in the Protocase enclosures to complete the hardware tasks (in work).

Also I needed to purchase or build a Real Time Clock module for the BBB. 

Analog I/O Cape Module:
I designed the Analog I/O Cape using Kicad as I described in a previous post. The design is a pair of Pulse-Width-Modulation (PWM) to 0-20 mA converters for feeding control signals to the I/P pump control Current-To-Pressure converters and a pair of resistors for converting the 4-20 mA current from the flowmeter to a 0-1.5 VDC signal to be measured by the BBB. I ordered the boards from Osh Park (Osh Park) along with breadboards for the Real-Time-Clock, described below. Noemi Fortes is loading the parts on the boards along with assembling the LCD module, BBB, power supplies etc into the Protocase enclosure that I described in a previous post.

Analog I/O Cape.

Real Time Clock (RTC) Cape (Board):
I found a possible RTC board, the (CircuitCo), but unfortunately they're out of stock everywhere. And that board isn't quite perfect, requiring a little rewiring to connect to the second I2L pins on the BBB. But I found a module at Adafruit, the (DS3231), that is probably more accurate than the CircuitCo board. However, the Adafruit module can't be plugged into the BBB, requiring a breadboard module. So I decided to get the Adafruit DS3231 modules and some breadboards from Osh Park (oshpark) along with some boards for the Analog I/O that I had reported on in a previous post. And I got some 46-pin connectors from Major League Electronics (46 Pin Connectors). My completed RTC module isn't beautiful, but I got it running well with the instructions from Adafruit.

Real Time Clock Cape Module.

I mounted the Adafruit DS3231 module upside-down to allow easy access to the battery.

Noemi Fortes is fabricating the controller systems and expects to have two systems completed by June 2. Noemi is an expert EE Fabrication Technologist and ex-coworker at the Lawrence Livermore National Laboratory. When Noemi completes the fabrication, I will check out my Analog I/O design and get the software installed and operational for Thomas Nguyen to test the systems and then take them to the painting facility in China. All that is coming up in my next posts.