Documentation updates for USR-W630 gateway#534
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…rza#510) Add configuration settings to docs for USR-W630 Modbus TCP - Modbus RTU setup
kellerza
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kellerza
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Thank you!
Interesting that you had to add it and in the fault-finding section there is a suggestion to remove it.
Can you measure the voltage drop over the resistor?
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| A 120 Ohm (brown-red-brown) resistor may be required for data communication between the adapter and inveter to occur without corruption. The resistor should be added between the A+B lines, such as in the example below. | ||
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| > NOTE: The resistor legs should be trimmed to a more reasonable length to ensure they don't accidentally short together. |
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You should trim the one in the picture 😆
Can you add size info to the image tags? It seems =400x400 is quite common on this page, but maybe the resistor should be =200x200?
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Haha yeah, I've been meaning to trim it, it was temporary, but you know how it is; as soon as it was functional, I now don't want the downtime.
I'll try and find a moment to get a multimeter on it tomorrow and get the voltage drop.
200x200 seems right for this image, I'll add the size info (I tried it originally before submitting but it broke the rendering in my IDE so I removed it thinking perhaps it was for specific types).
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The size is not 100% standard markdown. The docs use a plugin to enable sizing
Thanks!
Co-authored-by: Johann Kellerman <kellerza@gmail.com>
To answer this question; I tested the DC voltage drop across the resistor and found it to be approximately 0.1V when the bus is idle, and fluctuating around -0.22V when data was being transferred. I'm using a single twisted pair within about 3m length of Cat 6 unshielded cable between the SUNSYNK inverter (with a CAN/RS485 splitter) and the USR-W630. My initial testing was with a little over 0.3m of the same cable, and without the resistor the majority of the bus signals were corrupted, even initialisation of the inverter would fail 9 times out of 10. |
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Add note to docs about using a 120ohm resistor on W630 gateway (#510)
Add configuration settings to docs for USR-W630 Modbus TCP - Modbus RTU setup