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This blog post describes how to set up several Block Erupters in cgminer on Windows.

First here are the ingredients:

* Block Erupters.
* A powered USB hub with multiple USB ports. I had problems with random disconnecting and devices not being detected when I plugged more than 7 devices into one hub.
* A computer to plug them into and Windows 7 or 8 or something like that.
* A hashing pool account.
* The latest version of cgminer.
* Zadig ( https://github.com/pbatard/libwdi/wiki/Zadig )
* CGWatcher (optional)

To start mining, follow these instructions:

1. Plug in your USB hub.

2. Create a shortcut or batch file to cgminer like this:

C:\tools\cgminer-3.3.1-windows\cgminer-nogpu.exe -o [pool hostname]:[port] -u username.workername -p [password] –icarus-options 115200:1:1 –icarus-timing 3.0=100

Note; Previous versions of cgminer required you to specify the com port for the USB devices individually on the command line, but newer versions now detect the devices automatically.

3. Plug in all of your Block Erupters into the USB hub(s).

4. Start Zadig.

5. Go to Options > List All Devices.

6. Select the first instance of “CP2102 USB to Uart Bridge Controller”.

7. Click the Reinstall Driver button.

This will re-install the driver for the first Block Erupter (WinUSB).

8. Select the next USB to Uart Bridge Controller in the list.

9. Repeat steps 7 and 8 until each instance of the USB to Uart Bridge Controller is using the WinUSB driver.

Note: You must install the driver for each device individually.

Note: If you unplug one of the Block Erupters and plug it into a different USB port you have to install the driver again using Zadig.

10. When all of the Block Erupters are plugged in and all of them have the WinUSB driver installed, start cgminer using the shortcut or batch file you created.

cgminer will authenticate with the mining pool and then begin hotplugging devices and assigning work to them.

You will see cgminer enumerate each device as it detects it.

You can install CGWatcher (https://bitcointalk.org/index.php?topic=185553.0) to get a GUI on top of cgminer. Be sure to read the instructions.

Once you have CGWatcher running you can easily see which devices are functional under Devices > FPGA.

CGMiner reports one device for every time you plug something in and keeps those device numbers for the entire session, so if you unplug a device and plug it into another USB port you'll create one ghost FPGA slot in CGMiner and in CGWatcher.

If you see some devices that do not have any hashes in blue (not hashing), try unplugging that device and plugging it into another port.

If you get an error from cgminer about an invalid device, remember to use Zadig to re-install the USB driver for that device. You can find the one with the bad driver by scrolling through the devices in the list of All Devices in Zadig until you see the one with a different driver.

After you install the driver for a device that is plugged in you'll be prompted to restart your computer, but you don't really have to -- you can just unplug the device and plug it back in.

If you install the driver for a device that is plugged in it will take longer but it will succeed.

Notes:

* cgminer takes a long time to initialize the Block Erupter devices.
* cgminer will output that it is hotplugging each device one at a time.
* If all the devices are plugged in when cgminer is started cgminer will only show status information for the first USB device AMU0.
* You can see log information for all the devices by going into [D]isplay settings and toggling [P]er-device. However, you’ll still see only one AMU listed.
* The current total hashrate will fluctuate a LOT because cgminer seems to calculate the hash rate based on the amount of work returned by the attached hardware devices rather than the actual rate at which hashes are computed, so if several devices are returning work at the same time it artificially inflates the hash rate. The average is more reliable.
* I have discovered that of the USB hubs that had a lot of connectors, several of them had one or two bad ports, or they cannot actually support the number of devices they have ports for. It's probably a good idea to test if there are any bad ports. If I were smarter I'd use a voltage tester to see if the ports were undervolting when I plug in X number of devices, but I'm not that sharp. I suspect the problem is bad ports because when I move one of the Erupters from one port to another it starts working.

10 Erupters should get you about 3 Average Gh/s.

If you find this tutorial useful please send a small tip to 1LJU4GnHSM4ovdLNfaz4CmsacuznJewDh3

Thank you for this Tutorial. I have two quick questions

1) So, if ten can produce 3 Gh/s then that means the claims of 300 Mh/s is spot on. If I can only afford to get one or two Block Erupters right now, is it even worth it to run one or two?

2) I am using Linux and have BFGMiner installed. Since it is so similar to CGMiner, will it auto-detect the Block Erupter and assign work to it automatically?

very nice guide, kudos for writing it :)

Or you could:

1. Download bfgminer
2. Download VCP drivers
3. Install VCP drivers by double clicking the setup program
4. Plug in your hub and miners
5. Run bfgminer

Awful, awful lot easier.

I'm running 5 eruptors on Lubuntu linux.  It detected them right away, but I did have to start cgminer using sudo.
I don't know if BFGMiner has a rules file that you can install for the USB devices, but cgminer has one if you don't want to use sudo.

Awesome. Thanks! This is a great post. I am going to copy it into a text file and keep it on my desktop