P82B715TD Long Distance I2C Bus Extender I2C Mini Module

Hardware
1

Hello everyone,

I have two I2C bus extenders (https://store.ncd.io/product/p82b715td-long-distance-i2c-bus-extender-i2c-mini-module/) that are sitting on a control panel and the other end of these two extenders are about 7 and 10 meters from the panel going to Junction Boxes (JB). The 8m is on a CAT8 cable (with outer shield and pair shields) and the 10m is on a Cat6 cable (no shielding at all).

Setup
Setup.png899×622 34.7 KB

On the control panel, I have a 6-pin chassis connector. Inside the control panel is CAT6 for both of them with direct connection to the extender.

On both sides of the connection I have several I2C devices so I am using multiple I2C Cross-Over Adapters.

The pull-up jumpers are ON on both sides.

Now, the issue is with the communication reliability. When I connect my I2C devices over a short distance (directly on the panel), I receive the signals perfectly. However, when the I2C extender is in between, I do get a lot of losses and sometimes I am unable to communicate at all.

Few additional notes:

  • The communication loss is mainly on the 8m link, the other link is quite tolerable.
  • The communication loss on the 8m link was previously on CAT6, but due to the horrible response it was replaced with CAT8 hoping to improve the situation but with no effect.

Apologies if this is too long, but I tried to give as much information as possible.

Any advise to solve this issue?

Thanks and Regards,
Moath

2

Hi,
can you post picture of Tx and Rx side?

does it work fine if you reduce the cable length to 1 meter.

Thanks

3

These photos are before installing the pull-up jumpers:

Control Panel:

IMG_5351
IMG_5351.JPG4032×3024 2.09 MB

JB1:

IMG_5268
IMG_5268.JPG4032×3024 2.21 MB

JB2:

IMG_5269
IMG_5269.JPG4032×3024 1.93 MB

4

does it work in this case

5

Do you mean with the extender and 1 meter cable or without the extender and 1 meter cable?

Let me know, I will test it tomorrow.

Regards,
Moath

6

Hi,
with extender 1 meter cable.

Thanks

7

Hello,

So, I have replaced the CAT8 with the first CAT6, I’ve only cut it down to 1 meter.

The communication is OK (basically, I do not get the devices dropping when reading the I2C device list).

Thanks,
Moath

8

I will recommend trying stronger pullups on long range I2C screw terminals. ( one transmitter and receiver boards)

Currently it has 1K. You can install one more 1K in parallel.

9

Ok, will try that in my next visit

10

You might also look into the speed of I2C communications, lowering the speed can greatly improve distance on the I2C bus. I would recommend trying 100KHz in your application as a starting point.

11

Hello everyone,

I have tested with the additional pull ups with no success. As I needed an urgent resolution, I have tested another product with a differential based extender which worked after minor tweaking.

Thanks for the support
Moath