THC with Beckhoff EL5101 and THCAD2 => encoder signal loss
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09 Feb 2025 18:31 - 10 Feb 2025 17:18 #321088
by Sandro
THC with Beckhoff EL5101 and THCAD2 => encoder signal loss was created by Sandro
Hello everyone,
I am currently setting up my plasma cutter and encountering some initial issues that need resolution. One of these issues is the intermittent loss of my THC encoder signal, which occurs briefly at irregular intervals. Aside from this, the signal quality appears to be satisfactory in terms of noise. When the signal is lost for a few milliseconds, the torch attempts to compensate by raising itself before leveling again. I have attached a photograph (apologies for the quality) that illustrates the signal drop, followed by a voltage increase caused by the raised torch before it levels again.
I am utilizing a Beckhoff EL5101 incremental encoder interface in conjunction with a Mesa THCAD2. I have also tested with a THCAD300 I had available, and the issue persists. Additionally, I am employing hypersensing with a second THCAD2 and another Beckhoff EL5101, exhibiting the same behavior. Given that I previously used the THCAD300 with a 7i76e without issues, I suspect that the Beckhoff modules might be the cause.
Attached are three screenshots: one showing arc voltage at 0V, another displaying encoder frequency initially at 0V and then at 12V for testing purposes, and finally, the problematic screenshot showing encoder frequency during cutting. What options do I have to filter these signal drops effectively?
Thank you in advance for any advice or recommendations.
I am currently setting up my plasma cutter and encountering some initial issues that need resolution. One of these issues is the intermittent loss of my THC encoder signal, which occurs briefly at irregular intervals. Aside from this, the signal quality appears to be satisfactory in terms of noise. When the signal is lost for a few milliseconds, the torch attempts to compensate by raising itself before leveling again. I have attached a photograph (apologies for the quality) that illustrates the signal drop, followed by a voltage increase caused by the raised torch before it levels again.
I am utilizing a Beckhoff EL5101 incremental encoder interface in conjunction with a Mesa THCAD2. I have also tested with a THCAD300 I had available, and the issue persists. Additionally, I am employing hypersensing with a second THCAD2 and another Beckhoff EL5101, exhibiting the same behavior. Given that I previously used the THCAD300 with a 7i76e without issues, I suspect that the Beckhoff modules might be the cause.
Attached are three screenshots: one showing arc voltage at 0V, another displaying encoder frequency initially at 0V and then at 12V for testing purposes, and finally, the problematic screenshot showing encoder frequency during cutting. What options do I have to filter these signal drops effectively?
Thank you in advance for any advice or recommendations.
Last edit: 10 Feb 2025 17:18 by Sandro.
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- tommylight
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09 Feb 2025 20:32 #321111
by tommylight
Replied by tommylight on topic THC with Beckhoff EL5101 and THCAD2 => encoder signal loss
1. check wiring, literally remove each wire and re-seat it properly on the THCAD side and BeckHoff side
2. use a DVM with memory min/max and measure the 5V supply for the THCAD, if it goes under 4.75V change the power supply or add a 100-220Ufarad capacitor at the THCAD terminals and test again
3. set the divider higher or lower depending on how you look at it, if it is 1/32 set it to 1/64 and plot again.
2. use a DVM with memory min/max and measure the 5V supply for the THCAD, if it goes under 4.75V change the power supply or add a 100-220Ufarad capacitor at the THCAD terminals and test again
3. set the divider higher or lower depending on how you look at it, if it is 1/32 set it to 1/64 and plot again.
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09 Feb 2025 20:42 #321112
by rodw
Replied by rodw on topic THC with Beckhoff EL5101 and THCAD2 => encoder signal loss
Hmm, can you advise how long it drops to zero for? I did a component once that does a moving average of the torch voltage. You might be able to use it to bridge the outage...
Also you could try just using a 0-10 volt Ethercat analog input instead of the encoder input and thcad..
Also you could try just using a 0-10 volt Ethercat analog input instead of the encoder input and thcad..
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- Hakan
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09 Feb 2025 21:22 #321117
by Hakan
Replied by Hakan on topic THC with Beckhoff EL5101 and THCAD2 => encoder signal loss
Maybe the EL5101 can say when it doesn't have a good reading, or something along those lines. Obviously check cabling.
It seems you get zero Hz as frequency, that's a unique signal, THCAD always give some hundred/thousand of Hz.
Maybe some hal trickery to hold the last good value while frequency is zero. An own component perhaps.
It seems you get zero Hz as frequency, that's a unique signal, THCAD always give some hundred/thousand of Hz.
Maybe some hal trickery to hold the last good value while frequency is zero. An own component perhaps.
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09 Feb 2025 22:32 - 09 Feb 2025 22:41 #321126
by PCW
Replied by PCW on topic THC with Beckhoff EL5101 and THCAD2 => encoder signal loss
I would try at the THCADs 1/32 divide ratio
(The 1/1 ratio has relatively short pulse widths = 0.5 usec
which might be too short for the EL5101)
(The 1/1 ratio has relatively short pulse widths = 0.5 usec
which might be too short for the EL5101)
Last edit: 09 Feb 2025 22:41 by PCW.
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09 Feb 2025 22:36 #321127
by rodw
From your halscope plot, please let me know how long it lasts for.
Replied by rodw on topic THC with Beckhoff EL5101 and THCAD2 => encoder signal loss
Yes, a real time component could monitor the voltage and add a delay before it drops the voltage sent to plasmac. The moving average would do something similar. Say it averaged 1000 readings ( 1 second), it would take 1 second before it fell all the way to zero.Maybe the EL5101 can say when it doesn't have a good reading, or something along those lines. Obviously check cabling.
It seems you get zero Hz as frequency, that's a unique signal, THCAD always give some hundred/thousand of Hz.
Maybe some hal trickery to hold the last good value while frequency is zero. An own component perhaps.
From your halscope plot, please let me know how long it lasts for.
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10 Feb 2025 17:32 - 10 Feb 2025 17:33 #321175
by Sandro
Replied by Sandro on topic THC with Beckhoff EL5101 and THCAD2 => encoder signal loss
Hello everybody,
Thank you all very much for your inputs and recommendations. I can test most of them next weekend and report back to you.
I've tested the THCAD2 with a divider ratio of 1/128 and 1/64 already, but I can't remember if I also checked with 1/32. Will definitely try again.
I will also check the cabling again and the stability of the 5V power supply.
I think the frequency does not go to absolute zero but to less than 1 Hz (guess). I will also have a closer look at the duration of these drops. The EL5101 seems to provide some values for underflow, overflow and also the possibility to filter the frequency.
static const lcec_pindesc_t slave_pins = {
{ HAL_BIT, HAL_IO, offsetof(lcec_el5101_data_t, ena_latch_c), "%s.%s.%s.enc-index-c-enable" },
{ HAL_BIT, HAL_IO, offsetof(lcec_el5101_data_t, ena_latch_ext_pos), "%s.%s.%s.enc-index-ext-pos-enable" },
{ HAL_BIT, HAL_IO, offsetof(lcec_el5101_data_t, ena_latch_ext_neg), "%s.%s.%s.enc-index-ext-neg-enable" },
{ HAL_BIT, HAL_IN, offsetof(lcec_el5101_data_t, reset), "%s.%s.%s.enc-reset" },
{ HAL_BIT, HAL_OUT, offsetof(lcec_el5101_data_t, inext), "%s.%s.%s.enc-inext" },
{ HAL_BIT, HAL_OUT, offsetof(lcec_el5101_data_t, overflow), "%s.%s.%s.enc-overflow" },
{ HAL_BIT, HAL_OUT, offsetof(lcec_el5101_data_t, underflow), "%s.%s.%s.enc-underflow" },
{ HAL_BIT, HAL_OUT, offsetof(lcec_el5101_data_t, latch_c_valid), "%s.%s.%s.enc-latch-c-valid" },
{ HAL_BIT, HAL_OUT, offsetof(lcec_el5101_data_t, latch_ext_valid), "%s.%s.%s.enc-latch-ext-valid" },
{ HAL_BIT, HAL_IO, offsetof(lcec_el5101_data_t, set_raw_count), "%s.%s.%s.enc-set-raw-count" },
{ HAL_S32, HAL_IN, offsetof(lcec_el5101_data_t, set_raw_count_val), "%s.%s.%s.enc-set-raw-count-val" },
{ HAL_S32, HAL_OUT, offsetof(lcec_el5101_data_t, raw_count), "%s.%s.%s.enc-raw-count" },
{ HAL_S32, HAL_OUT, offsetof(lcec_el5101_data_t, count), "%s.%s.%s.enc-count" },
{ HAL_S32, HAL_OUT, offsetof(lcec_el5101_data_t, raw_latch), "%s.%s.%s.enc-raw-latch" },
{ HAL_U32, HAL_OUT, offsetof(lcec_el5101_data_t, raw_frequency), "%s.%s.%s.enc-raw-freq" },
{ HAL_U32, HAL_OUT, offsetof(lcec_el5101_data_t, raw_period), "%s.%s.%s.enc-raw-period" },
{ HAL_U32, HAL_OUT, offsetof(lcec_el5101_data_t, raw_window), "%s.%s.%s.enc-raw-window" },
{ HAL_FLOAT, HAL_OUT, offsetof(lcec_el5101_data_t, pos), "%s.%s.%s.enc-pos" },
{ HAL_FLOAT, HAL_OUT, offsetof(lcec_el5101_data_t, period), "%s.%s.%s.enc-period" },
{ HAL_FLOAT, HAL_OUT, offsetof(lcec_el5101_data_t, frequency), "%s.%s.%s.enc-frequency" },
{ HAL_FLOAT, HAL_IO, offsetof(lcec_el5101_data_t, pos_scale), "%s.%s.%s.enc-pos-scale" },
{ HAL_FLOAT, HAL_IO, offsetof(lcec_el5101_data_t, freq_scale), "%s.%s.%s.enc-freq-scale" },
{ HAL_FLOAT, HAL_IO, offsetof(lcec_el5101_data_t, freq_filter_gain), "%s.%s.%s.enc-freq-filter-gain" },
{ HAL_FLOAT, HAL_OUT, offsetof(lcec_el5101_data_t, freq_filtered), "%s.%s.%s.enc-freq-filtered" },
{ HAL_TYPE_UNSPECIFIED, HAL_DIR_UNSPECIFIED, -1, NULL }
};
I was also thinking of some moving average to filter the drops. But I don't know how I could implement this. Writing a custom HAL component?
Thank you all very much for your inputs and recommendations. I can test most of them next weekend and report back to you.
I've tested the THCAD2 with a divider ratio of 1/128 and 1/64 already, but I can't remember if I also checked with 1/32. Will definitely try again.
I will also check the cabling again and the stability of the 5V power supply.
I think the frequency does not go to absolute zero but to less than 1 Hz (guess). I will also have a closer look at the duration of these drops. The EL5101 seems to provide some values for underflow, overflow and also the possibility to filter the frequency.
Warning: Spoiler!
static const lcec_pindesc_t slave_pins = {
{ HAL_BIT, HAL_IO, offsetof(lcec_el5101_data_t, ena_latch_c), "%s.%s.%s.enc-index-c-enable" },
{ HAL_BIT, HAL_IO, offsetof(lcec_el5101_data_t, ena_latch_ext_pos), "%s.%s.%s.enc-index-ext-pos-enable" },
{ HAL_BIT, HAL_IO, offsetof(lcec_el5101_data_t, ena_latch_ext_neg), "%s.%s.%s.enc-index-ext-neg-enable" },
{ HAL_BIT, HAL_IN, offsetof(lcec_el5101_data_t, reset), "%s.%s.%s.enc-reset" },
{ HAL_BIT, HAL_OUT, offsetof(lcec_el5101_data_t, inext), "%s.%s.%s.enc-inext" },
{ HAL_BIT, HAL_OUT, offsetof(lcec_el5101_data_t, overflow), "%s.%s.%s.enc-overflow" },
{ HAL_BIT, HAL_OUT, offsetof(lcec_el5101_data_t, underflow), "%s.%s.%s.enc-underflow" },
{ HAL_BIT, HAL_OUT, offsetof(lcec_el5101_data_t, latch_c_valid), "%s.%s.%s.enc-latch-c-valid" },
{ HAL_BIT, HAL_OUT, offsetof(lcec_el5101_data_t, latch_ext_valid), "%s.%s.%s.enc-latch-ext-valid" },
{ HAL_BIT, HAL_IO, offsetof(lcec_el5101_data_t, set_raw_count), "%s.%s.%s.enc-set-raw-count" },
{ HAL_S32, HAL_IN, offsetof(lcec_el5101_data_t, set_raw_count_val), "%s.%s.%s.enc-set-raw-count-val" },
{ HAL_S32, HAL_OUT, offsetof(lcec_el5101_data_t, raw_count), "%s.%s.%s.enc-raw-count" },
{ HAL_S32, HAL_OUT, offsetof(lcec_el5101_data_t, count), "%s.%s.%s.enc-count" },
{ HAL_S32, HAL_OUT, offsetof(lcec_el5101_data_t, raw_latch), "%s.%s.%s.enc-raw-latch" },
{ HAL_U32, HAL_OUT, offsetof(lcec_el5101_data_t, raw_frequency), "%s.%s.%s.enc-raw-freq" },
{ HAL_U32, HAL_OUT, offsetof(lcec_el5101_data_t, raw_period), "%s.%s.%s.enc-raw-period" },
{ HAL_U32, HAL_OUT, offsetof(lcec_el5101_data_t, raw_window), "%s.%s.%s.enc-raw-window" },
{ HAL_FLOAT, HAL_OUT, offsetof(lcec_el5101_data_t, pos), "%s.%s.%s.enc-pos" },
{ HAL_FLOAT, HAL_OUT, offsetof(lcec_el5101_data_t, period), "%s.%s.%s.enc-period" },
{ HAL_FLOAT, HAL_OUT, offsetof(lcec_el5101_data_t, frequency), "%s.%s.%s.enc-frequency" },
{ HAL_FLOAT, HAL_IO, offsetof(lcec_el5101_data_t, pos_scale), "%s.%s.%s.enc-pos-scale" },
{ HAL_FLOAT, HAL_IO, offsetof(lcec_el5101_data_t, freq_scale), "%s.%s.%s.enc-freq-scale" },
{ HAL_FLOAT, HAL_IO, offsetof(lcec_el5101_data_t, freq_filter_gain), "%s.%s.%s.enc-freq-filter-gain" },
{ HAL_FLOAT, HAL_OUT, offsetof(lcec_el5101_data_t, freq_filtered), "%s.%s.%s.enc-freq-filtered" },
{ HAL_TYPE_UNSPECIFIED, HAL_DIR_UNSPECIFIED, -1, NULL }
};
I was also thinking of some moving average to filter the drops. But I don't know how I could implement this. Writing a custom HAL component?
Last edit: 10 Feb 2025 17:33 by Sandro.
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10 Feb 2025 19:08 #321181
by PCW
Replied by PCW on topic THC with Beckhoff EL5101 and THCAD2 => encoder signal loss
I would check the signal at the EL5101, it sounds like an electrical issue.
Is the EL5101 setup and wired for the THCADs differential signals?
(a THCAD cannot output a 0 frequency unless it has it's input polarity reversed or lacks proper 5V power)
Is the EL5101 setup and wired for the THCADs differential signals?
(a THCAD cannot output a 0 frequency unless it has it's input polarity reversed or lacks proper 5V power)
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15 Feb 2025 11:44 - 15 Feb 2025 11:50 #321628
by Sandro
Replied by Sandro on topic THC with Beckhoff EL5101 and THCAD2 => encoder signal loss
I have redone the cabling between the EL5101 and the THCAD300. Unfortunately I was unable to measure the min/max voltage on the 5V supply from the EL5101. So I have switched to a dedicated 5V power supply to power the THCAD and used a new twisted pair of cables to connect the differential signal to the A+ and A- phases of the EL5101.
Unfortunately the issue persists. Drop length is about 10ms and seems to be at random intervals. Frequency goes from 1824 Hz at 0V down to about 25 Hz. Divider ratio on the THCAD is currently at 1/64.
The second EL5101 with the THCAD2 for ohmic sensing behaves the same way. However for ohmic sensing, the drops are not really critical and and functionality is still given. Different story for the THC which raises the torch on every drop.
Unfortunately the issue persists. Drop length is about 10ms and seems to be at random intervals. Frequency goes from 1824 Hz at 0V down to about 25 Hz. Divider ratio on the THCAD is currently at 1/64.
The second EL5101 with the THCAD2 for ohmic sensing behaves the same way. However for ohmic sensing, the drops are not really critical and and functionality is still given. Different story for the THC which raises the torch on every drop.
Last edit: 15 Feb 2025 11:50 by Sandro.
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15 Feb 2025 14:49 - 15 Feb 2025 14:56 #321642
by PCW
Replied by PCW on topic THC with Beckhoff EL5101 and THCAD2 => encoder signal loss
Is this possibly a EL5101 bug or latency /communication issue?
Is the dropout always 10 ms? If so that more suggests a bug or
communication/driver problems than electrical issues.
Is the dropout always 10 ms? If so that more suggests a bug or
communication/driver problems than electrical issues.
Last edit: 15 Feb 2025 14:56 by PCW.
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