Friday, August 12, 2016

FZ-94 (3) – Connecting the Drives

The FZ-94 comes with two Delta VFD-L drive controllers often referred to as frequency drives. One controls the drum speed, the other the air flow via the fan speed. Both are operated manually via a dial. While Artisan can log roasts automatically by reading the three temperature values from the machine via its RS485/MODBUS connection, the drum speed and air flow, both of which have a considerable influence on the resulting roast, have to be manually marked via some user defined buttons or sliders.

That is a pity as both frequency drives built into the FZ-94 come with MODBUS support. However, those two controllers have not been connected to the RS485 ring by the factory up to this writeup. This was mostly to prevent potential communication hiccups that could be resulting from the faster communication speed required by those components. Since those hiccups are now prevented by Artisan v1.0, there is no longer a reason not to wire-in those drives. Indeed, Coffee-Tech Engineering just confirmed that from now on the FZ-94 will be delivered with those drive controllers wired up to the RS485 communication path.

Therefore, the remaining part of this post is for customers of previous FZ-94 builds. Luckily, it is quite simple to add those two missing wires by just plugging them into the controller on the one side and the RS485 hub on the other end. The only drawback is, we have to open the front panel of the machine. Let's do that!

Physical Setup

Luckily, the FZ-94 comes with a proper RS485 hub built in. That hub has 8 input channels and one output channel that connects to the external RS485-to-USB connector. All three temperature PIDs are already connected to that hub via its RJ45 sockets. So all we have to do is to plug-in wires from those two frequency drives into those spare RJ45 sockets.

The Delta VFD-L provides an RS485/MODBUS RJ11 connector. So we need two RS485 cables with an RJ11 plug on one end and an RJ45 plug on the other end.

For sure those cables can be purchased somewhere, but it was weekend and I got inspired by the Ben Heck show. So I MacGyver'ed me something from an CAT5 Ethernet cable with RJ45 plugs and a regular telephone cord with RJ11 plugs. Cutting both in half and wiring the opposite ends together resulted in two RJ45 to RJ11 cables.

UPDATE: I just got informed by Coffee-Tech Engineering that they can supply shielded cables produced by themselves at cost price. Those should be more reliable in the long run due to the shielding and simpler to install then my self-made alternative described below.

The RJ11 pinout can be found in the VFD-L user manual.

SG-/SG+ from the VFD-L side (RJ11 pin 3 and 4, respectively) need to be connected to D- and D+ (RJ45 pin 4 and 5, respectively).

While the CAT5 wire colors are standardized (RJ45 pin 4 is blue and pin 5 is blue/white), there are a number of color variations for RJ11 telephone cables. My telephone cable connects the green wire to RJ11 pin 3 and the red wire to RJ11 pin 4.

So the following wires needed to be connected

  • green wire of the telephone cord (RJ11/pin3) and blue wire of the CAT5 cable (RJ45/pin 4)
  • red wire of the telephone cord /RJ11/pin4) and blue/white wire of the CAT5 cable (RJ45/pin 5)

You see that I added a ferrite core on one end to filter out electro magnetic influence. This is not strictly needed, but might help to avoid communication errors.

Don't worry. If you accidentally connected those wires inversely, nothing can be broken by that. Just swap them and try again. 

To install our two RJ11/RJ45 wires we need to open the front panels of the machine. NEVER OPEN THE MACHINE WHILE IT IS CONNECTED TO THE POWER LINE. First we unscrew the panel holding the temperature PIDs to reach the RS485 hub that sits directly behind it and plug our cables in the sockets 5 and 6.

Next we need to open the panel that holds the two frequency drives and plug the ends with the RJ11 plugs of our cables into the RJ11 sockets of the frequency drives. We can route our two cables via a hole that connect the temperature PIDs department with the one of the frequency drives.

Drive Controller Setup

By default the frequency drives of the FZ-94 are not configured to talk MODBUS. We need to change their communication settings to make them answer data requests from Artisan.

We need to set

  • the MODBUS slaveID, here called the communication address (parameter 9-00), to d1 (Air Flow Controller) and d2 (Drum Speed Controller)
  • the MODBUS communication speed (parameter 9-01) to d2 (19200 baud), the same speed we did configure the temperature PIDs in the previous post
  • the communication protocol (parameter 9-04) to d6 (8N2; MODBUS RTU)

Artisan Setup

In a final step we need to tell Artisan how to access the data from the two frequency drives.  First we add two extra devices to record the extra data from the drives (menu Config >> Device, Extra Devices tab).

Next we configure the MODBUS input channel 5+6 (menu Config >> Serial, MODBUS tab). Above we set the slaveIDs of our drive controllers to 1 and 2, which we have to reflect here. The MODBUS register to read the current drive speed is 8451 and we need to set the divider to 1/100 as the data received is multiplied by 100.

Now we can turn the FZ-94 and Artisan ON and start logging the drive speeds too. Next we will show how to move the control of the drives from the physical dial to virtual sliders within Artisan.

NOTE: Please, study the linked manuals of the devices to understand the implications of any modifications you undertake as well as possible. Remember that you yourself are responsible for making sure the modifications are understood correctly and carried out precisely with care and common sense. We prepared our posts as careful as possible, but do not take any responsibility for remaining errors, mistakes or bad consequences that may result from you modifying any device based on the information given here.


  1. Hi, i'trying to achieve this with my roaster it also uses modbus rtu but another similar drive model ,the vfd-e, i'm searching the drive's manual, but can't figure out how to get the modbus register

  2. This comment has been removed by the author.

  3. This comment has been removed by the author.

  4. I received additional instructions from Coffee-Tech Engineering with which I was bale to get it to work.
    I am taking the liberty of posting it here as it is in the interest of FZ-owners to be able to set this up:
    "In order for the VFDs to communicate with the system properly they must be configured to eth correct parameters. The parameters are accessed by pressing prog/data, use the ↑↓ arrows to skip between parameter groups and press prog/data again to enter the group. Use the ↑↓ arrows to choose the desired parameter and press prog/data to enter it. The arrows are used also to change the values of the parameters and prog/data to save changes, then the screen will show END for few seconds to indicate that the changes were absorbed.
    These are the necessary parameters to change:
    Drum speed: 9-00 > D1. 9-01 > D2. 9-04 > D6.
    Airflow: 9-00 > D2. 9-01 > D2. 9-04 > D6."
    Hope thi helps.
    I was able to get everything set up on my end now.
    Thanks a lot and keep up the great work! :)

  5. And if you connect the RJ11 directly to the RJ45 port would not work the same? In the tutorial it is seen as void the rest of cables