Questions tagged [rj45]

For questions about Registered Jack 45, an 8 position 8 contact (8P8C) modular connector commonly associated with Ethernet and category 5 (Cat 5) cables. Consider using in conjunction with associated tags "connector", "ethernet", "cat5", "cables", etc., if applicable.

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Ebyte NS1 Design question

I am working on a new design dev board base on stm32h750 and Ebyte NS1 Ethernet Module . Ebyte give 2 design in data sheet . 1 one with a filter HR641680E 2 with a RJ45 build in 2KV electromagnetic ...
Khales Naim's user avatar
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1 answer
88 views

Ethernet with incorrect pinout still makes link?

I designed a board recently that accidentally had an incorrect pinout on the RJ45 jack for Ethernet. Instead of following TIA568, I instead routed it straight-through: Oh well, simple mistake, ...
Reid's user avatar
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1 answer
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Harmonics of Ethernet (100MBps) MLT-3 signals [closed]

I have EMC Issue (Radiation) as attached..where at some frequencies the emission levels are exceeding the limits.. I use 36V power and Ethernet (MLT3) for communication. These failing frequencies are ...
NICEGUY NICEGUY's user avatar
1 vote
2 answers
202 views

Ethernet Magnetics Polarity Swapping

Can I on the same pair (for Example A) to swap polarity on opposite side of transformer/magnetics? Update 1: Currently i use cross-over method to make lanes shorted and more easy to layout. Update 2:...
Radu G.'s user avatar
  • 23
2 votes
2 answers
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Lifting Pins on SMT RJ45 Connector

I'm running into an issue with a specific RJ45 SMT connector where the I'm getting at least 1 pin lifting on >50% of the boards that run through our reflow oven. The rest of the components on the ...
timroberts's user avatar
1 vote
1 answer
41 views

Useing a PoE RJ45 ICM Magnetics but not using it for PoE?

I plan on using the Bel G27-122T-015 (PoE ICM RJ45) but I don't need it for PoE. Can I just leave these pins unconnected? The ICM already has an internal Bob Smith termination.
miggyEE's user avatar
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5 answers
216 views

Do I need to keep twisted pair ethernet wires consistent down the entire cable?

I have an ethernet cable that is hooked up to a 20 foot long 24 AWG twisted pair cable. The twisted pairs are not twisted to the same wires like in the ethernet cable. Would this be a problem? I ...
buckithed's user avatar
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2 votes
1 answer
177 views

How do I connect an Ethernet Jack to LAN8720

I'm looking for a way to correctly connect an RJ45 socket to a LAN8720 chip, but cannot seem to find much information in the datasheets. Here is the datasheet for the LAN8720. And here is a data ...
JohnFahey's user avatar
-1 votes
1 answer
125 views

Hot-plugging current - TVS and ethernet

My question is based on this question over here In one of the comments, it is mentioned, "TVS on the media side would seem to invite short-circuit currents on hot-plugging. Putting it behind the ...
Freshman's user avatar
1 vote
1 answer
63 views

Easiest way to IP68 waterproof RJ45 cables/ports/splitting?

Consider the following simple daisy-chain arrangement: Protocol is MODBUS. Electrical standard is RS485. Cables also carry 12v DC power (Power over Ethernet) to the sensors. All cables are CAT5e ...
Noideas's user avatar
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1 answer
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Expected impedance across TX pair and RX pair on a functional RJ45 port

I'm using a sensor that has ethernet output. This new sensor is a replacement of yet another same sensor that seemed to have short-circuit like situation between its RX+/- pins. After connecting the ...
vyi's user avatar
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1 vote
0 answers
69 views

Direct Ethernet link between Raspberry CM4 and Jetson Orin Nano

I need to have high speed communication between Raspberry CM4 and Jetson Orin Nano modules on the same PCB. My question is: can I route them through Ethernet directly without the need for an isolator ...
j420hnny's user avatar
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0 answers
85 views

RJ45 Connector - Capacitors

I need an STM32F4 to communicate through LAN. An electronics technician provided a schematic (Version 1), of which I'm only showing the relevant part. I did my own research on the Internet and in the ...
Erwin Cornet's user avatar
1 vote
0 answers
133 views

Connect and disconnect Ethernet line

I need an IC to connect and disconnect the network cable line (TX+ and TX- lines to connect/disconnect) Can I use an analog switch IC?
hossein fathbag's user avatar
1 vote
1 answer
762 views

Ethernet transformer TD/TX sides

I’m curious as to the side the TD and TX side go to on an Ethernet transformer. I have drawn this schematic below and the datasheet for the Ethernet transformer hip is attached as well but I’m not ...
Rick James's user avatar
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1 answer
127 views

How to connect USB-to-RS485 adapter to RS485-RJ45 input of an LFP battery BMS? [closed]

I have Victron Multi 48/5000 connected to Cerbo GX. Works fine. Now I need to connect Cerbo GX to the LFP battery, to RS485 (because no CAN input). ...
Kirby's user avatar
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0 answers
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Shielding issues with RJ45 connectors

I've been dealing with a pretty nasty radiated emissions problem at work and I've pretty well exhausted any list of potential solutions/mitigation tactics to resolve this given the design constraints. ...
carbonboy25's user avatar
14 votes
1 answer
2k views

Why are non-conductive circuits designed on PCB?

This is the PCB of the network communication industry. What I know now is that after adding these redundant non-conductive circuits, the performance is improved from Cat3 to CAT5e. I really want to ...
David's user avatar
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1 vote
1 answer
101 views

Raspberry Pi ethernet socket type T-568A or T-568B

I'm using an rpi model B rev 2 as a wifi access point and need to run a long cat6 ethernet cable to its location from the router. It works fine with an off the shelf ethernet cable but I need to make ...
codebrane's user avatar
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2 answers
186 views

RJ45 termination in fast ethernet

I am working with fast Ethernet. My question is that we are using only two pairs in 100 Mbps. How will I terminate pin 4 and 5 and pin 7 and 8? Can I separately terminate magnetic center tap with a 75 ...
Manish Synergy's user avatar
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2 answers
165 views

Ethernet RJ45 Connector?

I have plenty of HR911130A in stock because they are small and directly compatible with Raspberry PI. For another project, the reference design recommends the 7498010210A connector, which is slightly ...
nowox's user avatar
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0 answers
448 views

Can I use an RJ45 plug designed for UTP with STP wire?

I have a non-standard application (model railroad) where I am planning to use CAT6 wiring between a custom made circuit board and a display panel. The circuit board will have RJ45 ports (using ...
Mark White's user avatar
0 votes
1 answer
149 views

EtherCAT Communication Testing

I am working on a device that uses EtherCAT. On one side, I have the standard EtherCAT Connector - an RJ45. On the other side, I would like to experiment with different connectors. For starters, I ...
Marko Jurisic's user avatar
0 votes
2 answers
611 views

Understanding 24 V PoE mode B magjack connections

Having just realised I have screwed up my board by stupidly swapping pins 4 & 5 on the magjack output, I have realised I don't properly understand the PoE power pins on the magjack. I wonder if ...
Neil's user avatar
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1 vote
1 answer
125 views

RJ45 PCB Design Transformer & MagJack

Designing a PCB board that supports RJ45 using W5500, yet I'm confused with two issues: Magnetic jack: Is it required? Is transformer required if Magnetic jack is used? Or are they unrelated? By ...
ahmed's user avatar
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1 vote
1 answer
197 views

Can I punch down regular hookup wire in an RJ45 Keystone Jack?

I'm planning to use CAT5e cable for a model railroad application and on the far end of the wire I am looking to use a keystone jack. My question is whether or not regular hookup wire can be punched ...
Mark White's user avatar
0 votes
3 answers
3k views

W5500 ethernet controller link problem

My design includes an STM32, a W5500 and this RJ45 connector which has a 1000pF/2kV capacitor. The problem is that when I connect a cable to the RJ45, the orange LED always blinks. This indicates no ...
berker's user avatar
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1 vote
1 answer
567 views

9 wires in a CAT5e cable?

I just cut open a CAT5e cable since I wanted it for a project which required several twisted shielded pair cables. To my surprise there were 9 wires with isolation? I was under the impression that ...
LukasL's user avatar
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0 votes
2 answers
117 views

Interfacing RJ45 to 3 pin RMII and bidirectionality

I am trying to add an Ethernet interface to a dev board (This board specifically). From looking at the schematics, I see that it has a 3 pin PHY input (GND, TRX+, and TRX-). From my understanding, a ...
bchang32's user avatar
0 votes
2 answers
245 views

Ethernet RJ45 M-F cable (socket <-> plug)

During renovation I've asked the electrician to use two long patch cables originally running from my router to create RJ45 sockets with the intent to later connect the router to the socket using a ...
peterph's user avatar
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1 answer
220 views

Not getting linkup on Ethernet with ESP32 MCU

I have an issue regarding ethernet with an ESP32. I have designed a hardware with an ESP32 and DP83848 phy for ethernet connection. The problem is I don't get link up from phy. I am running the ESP32 ...
ht_admin's user avatar
1 vote
0 answers
469 views

What to do with unused pins on a 1000BaseT RJMAG jack

Trying to figure out what to do with the unused wires heading into the magnetics on an RJMG2330A1610ER Ethernet/USB jack. Due to the craziness in manufacturing in the world I am forced to find a ...
tangomonky's user avatar
1 vote
3 answers
197 views

Ethernet Surge Protector Speed

I've been investing in some new surge protectors lately – a fraught process at best given the difficulties of comparing model and brand quality. Things were even trickier when looking into ethernet (...
fedora's user avatar
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0 votes
1 answer
1k views

How to connect Ethernet Magnetic/RJ45

I am connecting up my PHY to an RJ45 with magnetics and was wondering what I do with some pins on it. Here is the circuit for the Rj45 w/ magnetics. My questions are: do I connect pin 10 to the ...
Matty's user avatar
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0 votes
5 answers
114 views

Can I convert my dozens of laptop adapters into universal ones by using RJ-11 or RJ-45 connections?

I have accumulated dozens of laptop (and other) power bricks over the years. Some of them belong to a corresponding laptop or device, others just haven't been thrown away yet. I'm trying to make them ...
Zonker.in.Geneva's user avatar
0 votes
1 answer
172 views

protect RS485 from PoE

I have a board with two RJ45 connectors. One is used for an Ethernet port and the other one is for a RS485. The Ethernet is for Power over Ethernet. What are some suggestions to protect the RS485 port ...
Mark83's user avatar
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0 votes
1 answer
447 views

Difference between the two Ethernet magnetic topologies

Background Hello, I'm building up a PCB for a PoE module based on Microchip LAN8720 IC. The recommended schematic is shown in the following figure. I built up a prototype based on the Waveshare ...
Padmal's user avatar
  • 352
2 votes
1 answer
2k views

Center Tap (CT) pins in RJ-45 Connector

I'm not an Ethernet connector expert. I was wondering what are the CT pins in RJ-45 connector are used for. From a search in https://www.edaboard.com/ I found this interesting answer from a user ...
Firas Abd El Gani's user avatar
0 votes
1 answer
172 views

How to connect interfaces' shields?

I am designing a new PCB board these days, and I am confused about how to connect interfaces' shields. The interfaces on the board include USB, RJ45 and D-SUB, should them be connected directly to ...
JJbow's user avatar
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0 votes
0 answers
316 views

Transmitting I2S over 6ft

I've been looking at audio ADCs with most rated at 192Ksps with 24 bit audio. Typically the output is in I2S, but I understand that the signal is not intended to go far. I understand that HDMI can ...
LinuxGogley's user avatar
0 votes
1 answer
646 views

Manually Use LEDs on RJ45 Connector [closed]

I am using RJ45 connectors(2-406549-1) with built in LEDs, to transmit SPI lines for a microcontroller project(I needed CAT 6 cables for twisted data/ground pairs). I'd like to use those built in LEDs ...
Ryan W's user avatar
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1 vote
0 answers
69 views

DMX over RJ45 daisychain extra pins?

Im building a DMX controller that uses RJ45. (Controller as in lights are connected to it) I will obviously have 2 RJ45 jacks for daisy-chaining. What I was wondering is, I've seen that multiple ...
Randomaker's user avatar
1 vote
1 answer
349 views

10Gb link data transfer between FPGA && PC [closed]

I'm trying to transfer data from 10Gb ETH subsystem of FPGA to 10GB ETH card of PC. SFP, RJ45 and ETH cable comprise of this data transfer pipeline. The RTL code is ready for testing and I'm looking ...
iamgr007's user avatar
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0 votes
0 answers
125 views

Can I use 2 RJ45 magjacks (PCB mounted) used for pass through..on my PCB?

I need to put a pass through ethernet on my PCB. (rj45 to rj45). My circuit is similar to this guy.. I want to use my existing components. I have space on my chipplacer(yes I have a chipplacer line) ...
ferdio's user avatar
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0 votes
1 answer
129 views

How to fix a RJ45 connector patina without poison or with common tool?

The RJ45 connector from the wall of my house is rusted. The copper pins are covered by thick patina. The patina is so thick that it looks black. It definitely reduces communication quality so I would ...
Superuser's user avatar
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1 vote
1 answer
216 views

2 Ethernet jacks on a Device with ENC28J60 chip in with switch

I have an Ethernet device that works with Microchip's ENC28J60 chip perfectly. So if I want to connect a cable from a switch/controller, to device 1 (that has 2 RJ45 jacks), then have device 1 second ...
blackedpi's user avatar
2 votes
1 answer
329 views

How to properly read current of a PoE Mode A device?

I'm trying to measure the power consumption of a PoE device using Mode A. I assume I would need 2x current readings -- one for pin 1 (I1), one for pin 2 (I2), and then 1 voltage reading of from either ...
fullyjosh's user avatar
2 votes
1 answer
2k views

W5500 with POE functionality Link status ON with nothing plugged in?

I am working on a design that uses a W5500 for networking. I followed a reference schematic and believe all my connections are correct, however I am facing issues with the network connectivity. ...
Punchki's user avatar
  • 143
3 votes
2 answers
1k views

PCB design for RJ45 jack

I'm designing a PCB to host an Applanix APX15 GPS/inertial navigation device. The hardware integration manual (which seems not to be publicly available) shows that a 10/100 BaseT Ethernet is supported ...
Rob Skelly's user avatar
0 votes
0 answers
134 views

ENC28J60 Circuit Connected With 2 Magjack in Parallel

I'm using ethernet controller chip ENC28J60 and I need to have it connected to 2 magjack in parallel, but I'm unsure if I made a correct circuit, is this can work? Please advise me, thank you very ...
Qrenz's user avatar
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