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Ezb4- How To Extend The Servo Ports

Hi DJ,

Would you help to answer my question as below :

  1. I'm making a robotic but it has over 23 servo ports. Is it need to buy one more EZB4 to extend the servo ports? if yes, how to connect and let the ARC to know the extend servo ports?

  2. EZB4 can support the heavy duty servo (VDC 12V)?

  3. Will it reduce the power if servo ports are full ?

Thanks for your attention.

Ricky Ma


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  1. For an easy solution to add more servo ports to your robot project, yes, adding another EZ-B would be a better idea. It would be easier to connect together, and it will give you more ADC, i2c, UART and camera ports which you could use as well. In ARC, under the connection tab, you will see five fields to connect five EZ-B's.

To move a servo with multiple boards, in the servo controls, you can choose what board the servos are connected to. If you want to write scripts to move servos, this is how you would do it...

# A normal servo script connected 
# to "Board 0".

Servo (D0,90)
# This servo is connected to "Board 1"

Servo (1.D0,90)

The "1." in the second script is the number of the board the servo is connected to. The same can also be done with servo speeds. if you click here, you can read a thread I started about using multiple EZ-B's.

  1. You can use pretty much any servo with the EZ-B, so heavy duty servos will be fine. Providing you are using an adequate power source to power your 12v servos with correct voltage, and more importantly amps, it won't be a problem, but obviously 12v servos will use more power that a 7v servo. Click here to read a recent discussion about using adequate power supplies.

  2. To your last question about the EZ-B full for servos, this would depend on how many servos would be moving at the same time. Members have had 24 7v EZ-Robot servos connected to one board and have had no problems. However having 24 heavy duty 12v servos moving all at once, I'm not sure about. If the servo inrush current (when a servo begins to move) is too great, it could trip the poly fuse in the EZ-B. Moving one or a few servos that you mentioned at the same time should not be a problem.


You could also use an SSC-32 board to add up to 32 additional servos to your EZ-B. See


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Good point Alan. That one did slip my mind, and actually goes to answering a question I had recently about servo drivers.

Thanks. :)

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I just had a look at the SSC-32 servo board and it looks like it's been discontinued and replaced with the SSC-32 USB servo controller. I take it this works the same way as the old one using the UART connection?


The SSC-32 USB board works fabulous with the ezb... I have been using them with my inMoovs... As Alan mentioned there is support (ssc-32 control) already built into ARC for them... You access the 32 servo ports on the ssc-32 using the virtual ports in the autopositioner...

There is also a tutorial I wrote floating around here on how to drive the ssc-32 from a script as well....

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Excellent stuff. Ordering one now. Thanks for confirming.


Credit goes to Alan on this. His solution is simple to set up, connects straight to the EZ-B which frees up a lot of your digital ports, and is also a cheaper solution. :)


HI Steve G, Alan & Richard R,

Thanks everyone for your suggestion & information! I will buy one more SSC-32U USB servo Controller & EZB4 for my robotics!



Would I know that how to connect the Hardware SSC-32U USB servo Controller to EZB?


I am looking for a diagram to follow that highlights the following:

  1. Two (or more) EZB v4/2 linked together to take advantage of more ADC, i2c, UART and camera ports without having to connect to the EZB's over WiFi. a) In other words, how do you connect two or more EZB's to a PC through USB? My robot has a dedicated Mini ITX motherboard w/8GB of RAM, 2.8 GHz Quad-core Processor and four USB 3 ports + two USB Type C ports.

  2. The configuration has a camera connected to one of the EZB's camera ports (unless it is easier and more efficient to have the EZB v4/2 access a Web Cam connected to one of the USB ports on my ITX motherboard.

I have spent a day trying to find lessons and tutorials on how to accomplish the above, but am not seeing a complete picture.



Check this thread:


Use a usb camera instead of the ezrobot camera for an embedded system.



I read through that thread before I posted my question here. It was confusing as I did not see (undertand) how to go about connecting two EZBs to USB on my PC, bypassing WiFi and also using a camera.


You can’t use the camera - as the usb ezb page explains. You lose the camera port when connecting an ezb uart to a pc. This is because the camera port is used by the uart to the pc.

If you have a pc in your robot, use a usb camera. That’s why it’s okay to lose the camera port on the ezb because you simply add a usb camera in exchange.

If you don’t find the information that you’re looking for, it can’t be done :)


First and foremost, I want to thank you for taking time to address my question. I am very grateful. I also realize that I have not articulated my question very well.

I completely understand that I loose the option to connect a camera to the EZB once I have connected the EZB to my PC via USB. I also understand that I would connect a webcam to a USB port on my PC. What I am not clear about is how do I go about linking more than one EZB together if I am connecting one of them to my USB port on my PC.

Believe me when I say this, If you were in Michigan right now, I would let you smack me upside the head.

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You will need multiple USB ports on the computer or a USB hub, and one USB to TTL adapter per EZ-B. Each one will have its own combination port on the computer, then you just address them by computer port and use their EZ-B number as usual for multiple boards (board 0 is the default and the only one with a movement panel).

You can't chain them together.



Yeah, Alan’s got it. It all comes down to the amount of data that could be carried over a serial connection. The key word is serial - the data flows one bit at a time. The advantage to having multiple ezbs when requiring more ports is ARC is multitasking so commands are sent to each ezb at the same time. This way the number of ports doesn’t weigh down the communication.

One uart ttl per ezb and voila! :)

I just bought an amazon basics usb hub last week for $7 Canadian - that’s like 35 cents usd :D


This is brilliant. THANK YOU!

Okay, I am not looking for the cheapest solution, but I found this on Amazon. Would this work?

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Yep, that one should work. I know Will has used that one (or similar) with a direct connection to the EZ-B Camera.

I just don't know how the USB-to-Serial drivers are for that chip in particular. I've had troubles with prolific chips in the past. Maybe Will can offer some advice when it comes to the driver, it could just be built into windows but I doubt it. The unit might come with a driver CD though.


I can chime in here for sure. The Prolific is both recognized by windows 10 and you can download software and drivers from their website. The software will allow you to choose the max data rate. The one I have is 12m/sec max baud.



In reference to my post #19, the USB to TTL serial cables that I listed has 4 wired leads (+5V, GND, RXD and TXD). Is that sufficient? I do see some with six lead wires (GND, CTS#, 3.3v, TXD, RXD and RTS#).

Also... Is this the driver set you recommend?


I used my prolific to turn the EZ camera into a serial/usb Camera. I’ve not used it to connect the EZB to a computer. For that I used the ossep FTD-01. And it’s only 4 wires not 6 and 3.3 and 5 volts user selectable. I have one in all my robots, never had an issue.

And yes I believe that is the download site for prolific.



I was hoping you could answer this question. I have two EZ-B v4 on hand without the EZ-B v4/2 Comm Upgrade and was wondering if the upgrade was necessary if I am going down the path of utilizing the USB to TTL serial cables? Is there any advantage of using the v4/2 with a direct USB connection?

Note that I did order one EZ-B v4/2 as well as a EZ-B v4/2 Comm Upgrade kit last month and I am waiting for delivery, however if there is no advantage of using the upgrades with a direct USB to TTL connection, then I can begin working on my bots.


If you follow the instructions for usb conversion and the software is missing an option, then you need a firmware upgrade.

Here’s the link to instructions:


Ok! I will look into the firmware upgrade.

My question was more focused on the hardware. Do I need to do the physical upgrade to my original v4 EZ-Bs to make them EZ-B 4/2 (Comm 1 to Comm 2) ? Is there an advantage?


They NEED to be /2 comm, yes

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Okay! Fantastic!

I did place an order from the world famous EZ-ROBOT.COM website an EZ-B 4/2 and an EZ-B v4/2 Comm Upgrade kit. Looks like I need to order another EZ-B v4/2 Comm Upgrade kit so all three of my EZ-Bs will be rocking. :)

Thank you.