Monday, June 3, 2013

Device Selection



There are a number of devices to monitor or control your roaster that are supported by Artisan. Which one to choose? Let's look at the key features of the available choices.

UPDATE (3.4.2018): The most up to date information on devices and machines supported by Artisan can be found on its new Web page at https://artisan-scope.org.


Some devices just allow to read in the temperature values of the connected probes. Others also take commands that can control the heater or fan of your roaster among others. Some devices let you connect only one probe, others up to four. Having at least two channels makes sense to gather both, Environmental Temperature (ET) and Bean Temperature (BT).

Devices are connected to Artisan either via a an external serial/USB connector or via a RS485/USB for Modbus devices. For various reasons Artisan does not support USB HID devices. A few devices have a build in serial/USB converter and feature a direct UDB connection. However, internally they still talk a standard serial protocol and not the USB HID one. Some of those converters offer an optical isolation that helps to eliminate some ground loops between the ground of your computer and that of the device, which can lead to spikes in the roast graph. In any case you have to ensure that a corresponding driver for the device is available for your computing platform is available. There are cases were for example the meter features a FTDI chip, but the corresponding driver available from FTDI does not support that specific device unique id (most likely for some licensing reasons). So better check before purchasing!

Other differences concern the serial speed of the connection between the device and your computer,  additional device features and the power supply. The maximum speed of this serial connection supported by the device can range from 2400 bauds to 19200 baud or more. Furthermore, some devices offer data logging capabilities by featuring an internal memory store. However, with Artisan connected this memory is not used nor needed. Finally, some devices run from battery only, others  need an external power source. Few support both, external as well as battery power.

Of course, the price of a device depending on its feature set (to some extend). Usually, the more channels are supported the higher the price. Especially an internal memory adds to the price tag.

Deciding on the number of temperature channels in the device selection process is somewhat simplified by the ability of Artisan to communicate to an (almost) unlimited number of devices. So instead of selecting immediately a four channel device, it is possible to start with a dual channel device and add a four channel device later to end up with six channels.

So let's take a look now at the available options, somewhat categorized by device type and number of input channels.

Single Channel Temperature Meters

  • CENTER 300 / VOLTCRAFT K201 / VOLTCRAFT 300K
    • Single K-Type
    • RS232 Interface (9600-8N1)
    • 9V Battery only
    • Software optional
  • CENTER 302
    • Single K/J-Type
    • RS232 Interface (9600-8N1)
    • 9V Battery only
    • Software optional
  • CENTER 305
    • Single K-Type
    • RS232 Interface (9600-8N1), cable included
    • 9V Battery only
    • Software included
  • Yocto-PT100
    • RTD/PT100
    • USB
    • USB-powered
    • Open-source driver

The single temperature meters listed above are rather simple and cost-efficient. If it is only the BT curve you are interested and don't want to spent too much money they are a good option. Note that the CENTER 300 is also on the market under the label VOLTCRAFT K201 and 300K with minor differences.

Dual Channel Temperature Meters

  • CENTER 301
    • Dual K-Type
    • RS232 Interface (9600-8N1)
    • 9V Battery only
    • Software optional
  • CENTER 303 / VOLTCRAFT 302KJ / VOLTCRAFT KJ202
    • Dual K/J-Type
    • RS232 Interface (9600-8N1)
    • 9V Battery only
    • Software optional
  • CENTER 306 / VOLTCRAFT K202
    • Dual K-Type
    • RS232 Interface (9600-8N1), cable included
    • 9V Battery only
    • Internal memory
    • Software included
  • Omega HH506RA / EXTECH 421509
    • Dual K/J/T/E/R/S/N-Type
    • RS232 Interface (2400-7E1)
    • Internal memory
    • 9V Battery only
    • Optional optical-isolated serial2USB converter
  • Amprobe TMD-56 / Omega HH806AU / Mastech MS6514
    • Dual K/J/T/E/R/S/N-Type
    • Built in USB to serial converter (19200-8E1)
    • Internal memory
    • 4 x 1.5V AAA Batteries or external power
  • Omega HH802U
    • Dual K/J-Type
    • Built in USB to serial converter (19200-8E1)
    • 4 x 1.5V AAA Batteries or external power
  • myPCLab
    • Dual K/J/T/E/N/R/S/B/Pt100/RTD-Type + internal ambient temperature
    • ASCII or Modbus RTU protocol
    •  Build-in USB interface (only supported by Windows, no Mac/Linux drivers available)
    •  USB-powered
  • Yocto-Thermocouple
    • Dual K/E/J/N/R/S/T-Type
    • USB
    • USB-powered
    • Open-source driver
The dual temperature meters are perfect for the standard use of Artisan to log the BT and ET temperature curves. If your probe is a K-Type, which is the standard for measuring BT/ET in a coffee roaster, you can choose from any of the above meters. The Amprobe is especially interesting due to its competitive price tag (see this previous post to learn how the Amprobe and Artisan helped to investigate the Londinium group temperature stability). The Omega HH506RA (or its EXTECH variant) is interesting for its optical-isolated serial2USB converter. However, this converter is an add-one that has to be purchased separately and the fixed serial speed of that device is quite low (although it works well with Artisan). All of the devices listed here exclusively run from battery, but for the last one which does not need any external power but for the USB connection. The myPCLab is interesting as it does not connect via the serial protocol, but via Modbus to Artisan and comes with a corresponding converter build-in at a very reasonable price (more details on the myPCLab and its Modbus connection are given in this post). It also supports a wide range of probe types and features as third channel the internal temperature of the device, which can be used to automatically fill the ambient temperature field in the Artisan Roast Properties dialog.

Four Channel Temperature Meters

  • CENTER 304 / VOLTCRAFT K204
    • Four K-Type
    • RS232 Interface (9600-8N1)
    • Software optional
    • 9V Battery or external power
  • CENTER 309 / VOLTCRAFT K204 / Omega HH309 / General Tools DT309DL
    • Four K-Type
    • RS232 Interface (9600-8N1)
    • Internal memory
    • Software included
    • 9V Battery or external power
Those 4 channel meters in the list above all basically identical. Just that the CENTER 304 (and one of the two VOLTCRAFT K204, no typo here!, does not include any data logging capability. However, that does not matter for its use with Artisan. Therefore, selecting the CENTER 304 over the CENTER309 makes sense as it is usually the cheaper device (so take care, there are two different devices labeled VOLTCRAFT K204, but they can easily be distinguished by price). However, if you think you need four channels consider also the Arduino-based TC4 option listed next.

Phidgets

The Phidgets are up to now the fastest (in terms of communication speed) and cheapest 4 channel option. They are also the only devices that communicate directly via USB instead of the slow and error prune serial2USB connection all other meters are using. Phidgets are supported by Artisan from v0.7 on. From Artisan v0.8 on Phidgets can be remote accessed too, via Ethernet networking or WiFi using another computer or a Phidget SBC.  The Phidgets InterfaceKits (eg. SBC and 1018) are now also supported and listed below.

The new additions Yocto-PT100 and Yocto-Thermocouple listed above are similar to Phidgets in concept and use.

Arduino/TC4

  • Arduino/TC4
    • Four K/J/T-Type
    • Build-in USB interface (19200-8N1)
    • USB-powered
    • Optional control hardware (Hottop Roaster Interface)
    • Optional PID software
The Arduino/TC4 is an interesting option for those that do not worry much about handling electronics without a case. The TC4 is a 4-channel temperature probe shield that can be attached to the standard Arduino UNO open-hardware device. There is also an integrated product that combines a variant of the UNO with the TC4 in one package, named TC4C. Furthermore, the HT Roaster Interface was developed as add on to the TC4/TC4C stack to allow the control of the Hottop home roaster via serial commands that can be assigned to sliders or buttons in Artisan (see this post for details). From Artisan v0.8 on the PID functionality provided by the aArtisan firmware v3 is supported.

Multi-Meters

Currently Artisan supports two (rather cheap) Multi-Meters that can be used to read in volts and current from connected (sensor-)probes like the air-pressure in your duct. The TE VA18B also supports one temperature channel connecting to a K-Type probe.
  • Omega HHM28
    •  AC/DC volts and current
    •  RS232 Interface (2400-8N1)
    • 9V Battery only
  • TE VA18B
    • single K-Type
    • AC/DC volts and current
    • optical-isolated USB Interface (2400-8N1)
    • 9V Battery only
  • Phidgets I/O Boards (1010, 1011, 1018, 1019, 1073)
    • up to 8 analog inputs (0-5V)
    • USB interfaced and powered

PIDs

  • Fuji PXR/PXG 4 & PXR/PXG 5 PID
    • Modbus RTU option (needed to connect to Artisan)
    • Specific Artisan support implemented
  • Watlow EZ-Zone PM6
    • Connects via Modbus to Artisan
    • No direct PID control support by Artisan yet
    • built into some San Franciscan roasters
  • ENDA EUC422
    • Connects via Modbus to Artisan
    • No direct PID control support by Artisan yet
    • built into some Toper roasters
  • Delta DTA/DTB
    • Connects via Modbus to Artisan
    • No direct PID control support by Artisan yet
    • built into some Oz roasters

All those PID potentially allow to control some aspects of your roaster, depending on your exact hardware setup. Artisan v0.6 is able to send Modbus commands to modify registers in those devices that might have the effect to change the speed of your roasters drum or the level of heat supplied by its heater. Consult the manual of your devices to find out which commands to be used and configure Artisans sliders and buttons correspondingly.

The Fuji PID receives some extra support by Artisan. If Fuji is selected as device, there is an extra setup button set allows you to change the corresponding register maps via some nice UI.