Labjack T7, PWM and Daqfactory

Yes, start with the "Device Configuration" section here:

https://labjack.com/support/software/examples/ljm/daqfactory

Note that if your configuration is always the same, you can just do it once in Kipling and save that configuration as the power-up default.

I updated the "Device Configuration" section a little bit:

https://labjack.com/support/software/examples/ljm/daqfactory

Sounds like you are wanting to use method #2A as described in that section.  Yes, you can use eWriteName to write values to the 5 configuration registers you listed.  See the example LJM_Basic.ctl, as it does just that, writing to 4 different configuration registers to set analog input ranges.

That is the configuration.  Your next question will likely be how to change the duty-cycle (CONFIG_A) in DAQFactory as your program runs.  For that, I would start with something similar to what you see for DAC0 or FIO1 Output in the basic example.  So first define a channel in the DF Channels list using the "Special", and then make a Variable Value Display on a Page that writes a new value to your Channel when clicked.  Then you might be interested in setting the output based on an input read:

https://labjack.com/support/ud/df-lj-app-guide/7.1

A digital output can directly control most SSRs, but in the case of PWM output it cannot directly control most LEDs.

Understand that digital I/O have 3 states:  input, output-high, and output-low.  To do direct control of an SSR, you connect it for sinking control (VS & DIO) where you change the DIO between input (off) and output-low (on) to control the SSR.  PWM drives a digital output between output-high and output-low, not input and output-low.

https://labjack.com/support/app-notes/controlling-relays

As a recap for others, you are handling device configuration by using method 2A from the "Device Configuration" section here:

https://labjack.com/support/software/examples/ljm/daqfactory

I see that you are setting the Clock0 roll value, but you do not enable the clock.  Do you enable it somewhere else?

For each of your 3 PWM outputs, you enable the feature and then set the index.  It would be more correct to set the index (and also set an initial value for config-a), and then enable.

Are you wanting to also add thermocouple configuration?  For each analog input, you would write to AIN#_EF_INDEX and perhaps some of the
AIN#_EF_CONFIG_ registers if needed.

Your watchdog configuration looks good.  You have configured the watchdog to reset the T7 whenever it does not receive any communication from the host for 15 seconds.  Note that if you close DAQFactory, without disabling the watchdog, the device will then reset every 15 seconds as long as no software is talking to it.  There is nothing wrong with this, but if you want to avoid it you might post on AzeoTech's forum to ask about how to run a script when DF closes so you can disable the watchdog:

http://www.azeotech.com/board/

Note that the watchdog registers have _DEFAULT at the end, which means they are immediately saved to non-volatile memory:

https://labjack.com/support/datasheets/t7/io-config-default

The DIO-EF and AIN-EF configuration in your script is not immediately saved.  That means that if the T7 reboots while your program is running, these will go back to default condition.  You could have some sort of error handling that detects this and re-runs the configuration script at that time, or an easy solution would be to just save your configuration by adding a write of IO_CONFIG_SET_DEFAULT_TO_CURRENT = 1 at the end of your script.

> LJM_eWriteName(identifier, "AIN0_EF_INDEX",22)
> LJM_eWriteName(identifier, "AIN0_EF_CONFIG_A",1)

The first line is enabling the thermocouple feature for type K.  The second line is setting the output units to degrees F, rather than the default of degrees C.  You have not written anything for config-b (AIN0_EF_CONFIG_B), so are using the default which is device temperature.

https://labjack.com/support/datasheets/t7/ain/extended-features/thermoco...

https://labjack.com/support/datasheets/t7/internal-temp-sensor

https://labjack.com/support/app-notes/thermocouples

https://labjack.com/support/app-notes/thermocouples/t7

USB or Ethernet?

For both, if you power-cycle the T7 while your program is running does it recover properly?

For Ethernet, if you disconnect/connect the Ethernet cable while your program is running does it recover properly?

Please update to LJM 1.11 using the 12-4 installer so you are using the latest library.

I posted 2 examples and am tagging these for a couple other people to look at.  Both examples simply read 1 analog input.  1 use D#=0 and the other uses D#=IP.  Neither comes back when I disconnect then reconnect the Ethernet cable.

I'm testing with:

T7 Firmware 1.0192
LJM 1.11
DAQFactory Express 5.91 Build: 2233

No.  Sorry but the LJM guy who needs to tackle this is on vacation this week, so can't look at it until next week.

I did a test in LabVIEW and was able to cause the same problem there.  I ran "LJM_eReadName Example.vi" using Ethernet, but put a breakpoint before the Close call so I could stop the VI before it closed the Handle.  I then just ran-continuously the "LJ_eReadName.vi" sub-vi with that Handle number, disconnected the Ethernet cable until I got the 1239 error, then reconnected the Ethernet cable, but kept getting the 1239 error forever.  I feel that LJM should automatically heal this connection but is not.

In other languages (including LabVIEW) besides DAQFactory, we could close the handle and do a re-open, but DF needs the auto-reconnect to work here.

#25:  No new news.  This problem is pretty complex in LJM, and lots of vacations going on right now, so unfortunately we have not resolved this as quick as usual.  I would add that normally Ethernet runs forever without any communication disruptions, so you usually don't need the reconnect functionality.  This might suggest a further problem in your case.

#26:  I just tried a direct Modbus write to 44300 using some LabVIEW-Modbus VIs and it worked fine for me.  Here are the packets sent and received:

Sent:  0, 0, 0, 0, 0, B, 1, 10, AD, C, 0, 2, 4, 0, 1

Received: 0, 0, 0, 0, 0, 6, 1, 10, AD, C, 0, 2

LabJack uses a significant # of Modbus registers to allow you access to all the features of the T7.  For this reason, all registers are numbered from 0, and because there were so many, they had to use registers in the 30,000 and 40,000 range.  These registers can confuse some software, including DAQFactory, into thinking that you are actually using the 40,001 notation that many manufacturers use.  So, when you specify 44300 it strips the 4 and subtracts 1.  This may even make some of your other readings suddenly not work as DAQFactory does the same thing to all registers.  To get DAQFactory to stick with 0 indexed notation, simply create a channel with a tag > 50,000 and read it once.  It doesn't have to be a real tag.

Hi Johan,

If you're still using LJM and still have Ethernet reconnection issues, please try running the latest beta installer, which has LJM 1.1100. Ethernet reconnection works well for my tests.