<p>Are you sure that the A8 connects to a PC using a serial port? I don't know of any 3D printers that do that. Typically, 3D printers connect to PCs using a USB connection, and there will be a type-B USB socket on the printer.</p>

<p>However, there will be a USB bridge chip on the printer's controller board that connects the microcontroller to the USB socket. This bridge chip does have a serial port that is used to communicate with the microcontroller. Typically, these serial ports operate at 115,200 bits per second (115.2 kbps), although this may vary. Some USB bridge chips are capable of operating at 250kbps.</p>

<p>Often, the software running on the PC needs to know what speed the serial port on the bridge chip runs at, in order to send data at a suitable rate. Of course, the USB connection is capable of handling data at a much higher rate, but the microcontrollers used in many 3D printers are not capable of handling such speeds.</p>

<p>Note that the USB bridge chip on the printer may appear as a virtual COM port on a PC.</p>

CC BY-SA 3.0
2018-01-24T04:39:18.200Z
@Mick Some computers detects as COM the arduino using the USB port, Serial ports normally uses COM1. USB ports can be detected as COM2 or more, for example my computer detects COM5, COM8,COM21, depending whicn HUB USB i'm using. The speed connection will depend on the baud rate which the Arduino was programmed sometimes @ 9600 for low processing and higher rates for high computing.
Fernando Baltazar
CC BY-SA 3.0
2018-01-12T10:39:21.880Z
You do know that a COM port is a serial port, right? (virtual or otherwise)
Onno
CC BY-SA 3.0
2018-01-12T10:59:17.523Z
@Onno I know about virtual serial ports, but a maximum baud rate of 9600? That sounds like a hardware (RS232) port to me (or at least, Windows thinks that it is).
Mick
CC BY-SA 3.0
2018-01-13T09:55:42.897Z
Don't know what happened , didn't change a thing but all of a sudden the pc started to talk to the printer.......weird.  Can only think my norton was away to internetland to see if it was OK to talk to this new stranger.  Thanks for the answers though.
Plodmore
CC BY-SA 3.0
2018-01-10T22:03:36.680Z
2018-01-10T22:03:36.680Z
Mick
<p>My A8 just started doing this. </p>

<p>I shut down repetier server, and voila, all is good! Since I will go do OctoPi eventually, I just uninstalled RS.</p>

CC BY-SA 4.0
2019-02-15T18:30:25.313Z
Hi, and welcome to SE 3D Printing! Whilst your answer may be technically correct, it *is* rather terse, and, as such, it has been recommended for deletion, unfortunately. If you could expand it then you may get a more positive response. I would recommend that in addition to reading some highly voted answers to gauge the standard expected, that you take a look at the help section relating to [answering](https://3dprinting.stackexchange.com/help/answering) questions, in particular [answer], and take the [tour] for more information on how stack exchange works. Thanks :-)
Greenonline
CC BY-SA 4.0
2019-02-15T01:52:06.290Z
2019-02-15T01:52:06.290Z
BotanyBayDon
<p>Sorted. Repetier Server was hijacking my com port. Uninstalled it and Repetier host worked fine. As I have no desire to monitor or control prints remotely I have no use for the server software.</p>

<p>Hope that helps others.</p>

CC BY-SA 3.0
2018-01-23T15:27:00.027Z
2018-01-23T15:27:00.027Z
Plodmore
<p>I am still at calibration stage and need some info from the PCB. I connected the USB and ran Repetier. The PCB wants to talk at a higher baud rate than my serial port says it can do. I tried setting the serial port to its highest setting 125k and reduced the PCB baud in Repetier setting to 125k. No joy. PC port reverts to 9600 every time I check it. Thoughts?</p>

<p>PC running Windows 7 Home Premium 32bit.</p>

<anet-a8>
Connecting Anet A8 to PC issue
Plodmore
# Connecting Anet A8 to PC issue

(Asked by: username_0 on 2018-01-10)

I am still at calibration stage and need some info from the PCB. I connected the USB and ran Repetier. The PCB wants to talk at a higher baud rate than my serial port says it can do. I tried setting the serial port to its highest setting 125k and reduced the PCB baud in Repetier setting to 125k. No joy. PC port reverts to 9600 every time I check it. Thoughts?

PC running Windows 7 Home Premium 32bit.

**Tags:** anet-a8

---

## 3 answers

### Answer by username_0 on 2018-01-23. Score: 4 | Accepted answer

Sorted. Repetier Server was hijacking my com port. Uninstalled it and Repetier host worked fine. As I have no desire to monitor or control prints remotely I have no use for the server software.

Hope that helps others.


---

### Answer by username_1 on 2018-01-10. Score: 0

Are you sure that the A8 connects to a PC using a serial port? I don't know of any 3D printers that do that. Typically, 3D printers connect to PCs using a USB connection, and there will be a type-B USB socket on the printer.

However, there will be a USB bridge chip on the printer's controller board that connects the microcontroller to the USB socket. This bridge chip does have a serial port that is used to communicate with the microcontroller. Typically, these serial ports operate at 115,200 bits per second (115.2 kbps), although this may vary. Some USB bridge chips are capable of operating at 250kbps.

Often, the software running on the PC needs to know what speed the serial port on the bridge chip runs at, in order to send data at a suitable rate. Of course, the USB connection is capable of handling data at a much higher rate, but the microcontrollers used in many 3D printers are not capable of handling such speeds.

Note that the USB bridge chip on the printer may appear as a virtual COM port on a PC.

> **Comments:**
> **username_3**: You do know that a COM port is a serial port, right? (virtual or otherwise)  
> **username_1**: @Onno I know about virtual serial ports, but a maximum baud rate of 9600? That sounds like a hardware (RS232) port to me (or at least, Windows thinks that it is).  
> **username_0**: Don't know what happened , didn't change a thing but all of a sudden the pc started to talk to the printer.......weird.  Can only think my norton was away to internetland to see if it was OK to talk to this new stranger.  Thanks for the answers though.  
> **username_2**: @Mick Some computers detects as COM the arduino using the USB port, Serial ports normally uses COM1. USB ports can be detected as COM2 or more, for example my computer detects COM5, COM8,COM21, depending whicn HUB USB i'm using. The speed connection will depend on the baud rate which the Arduino was programmed sometimes @ 9600 for low processing and higher rates for high computing.  

---

### Answer by username_4 on 2019-02-15. Score: -2

My A8 just started doing this.

I shut down repetier server, and voila, all is good! Since I will go do OctoPi eventually, I just uninstalled RS.

> **Comments:**
> **username_5**: Hi, and welcome to SE 3D Printing! Whilst your answer may be technically correct, it *is* rather terse, and, as such, it has been recommended for deletion, unfortunately. If you could expand it then you may get a more positive response. I would recommend that in addition to reading some highly voted answers to gauge the standard expected, that you take a look at the help section relating to [answering](https://3dprinting.stackexchange.com/help/answering) questions, in particular [answer], and take the [tour] for more information on how stack exchange works. Thanks :-)  

---

