A cheap USB relay available from Ebay with 1,2,4 or 8 relay output. The double throw relay ratings are 10A 250VAC each.
The USB device is HID compatible and comes with Windows control software. This code can control the relay vi HIDAPI which is a cross platform library. This code was tested under linux both on x86 and Raspberry Pi ARM. The program is command line only as it is likely to be used by shell scripts.
The output of lsusb for the device is:
Bus 001 Device 003: ID 16c0:05df Van Ooijen Technische Informatica HID device except mice, keyboards, and joysticks
# lsusb -v -d 16c0:05df
Bus 001 Device 003: ID 16c0:05df Van Ooijen Technische Informatica HID device except mice, keyboards, and joysticks
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.10
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 8
idVendor 0x16c0 Van Ooijen Technische Informatica
idProduct 0x05df HID device except mice, keyboards, and joysticks
bcdDevice 1.00
iManufacturer 1 www.dcttech.com
iProduct 2 USBRelay2
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 34
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 20mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 3 Human Interface Device
bInterfaceSubClass 0 No Subclass
bInterfaceProtocol 0 None
iInterface 0
HID Device Descriptor:
bLength 9
bDescriptorType 33
bcdHID 1.01
bCountryCode 0 Not supported
bNumDescriptors 1
bDescriptorType 34 Report
wDescriptorLength 22
Report Descriptors:
** UNAVAILABLE **
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0008 1x 8 bytes
bInterval 20
Device Status: 0x0000
(Bus Powered)
http://www.signal11.us/oss/hidapi
HIDAPI is a fairly recent addition to linux and is available as a package for Fedora 20 but not for Pidora (F18). The package was built for Pidora (Fedora 18) using the F20 hidapi source package.
This code is a maintained package in Debian (and Raspian). Use normal apt-get commands:
$ sudo apt-get install usbrelay
The packages are available in Fedora36+
$ sudo dnf install usbrelay-common python3-usbrelay usbrelay-mqtt
Other Linux platforms will need to build the source, see below
The relay modules does not set the USB serial number but has a unique serial when the HID device is queried, the current state of the relays is also sent with the serial. The HID serial is matched and the ON/OFF command is sent to the chosen relay.
The usual make, make install dance assuming the hidapi and hidapi-devel packages have been installed. Note that there are two options for the hidapi library: hidapi-hidraw or hidapi-libusb. Different distributions have better results with one or the other. YMMV.
$ sudo apt-get install libhidapi-dev libhidapi-hidraw0 git
$ git clone https://github.com/darrylb123/usbrelay
$ cd usbrelay
$ make
$ sudo make install
### Test with a usbrelay plugged in
$ sudo usbrelay
### Build the python interface using the instructions below
To choose the alternative hidapi libraries, add the option to the make command line
### hidapi-hidraw - This is the default if no option is given
$ make HIDAPI=hidraw
### hidapi-libusb
$ make HIDAPI=libusb
You can also build using Docker. Assuming you have Docker installed (only tested with version 18), execute the build script:
$ ./build.sh
The usbrelay binary, libusbrelay.so and libusbrelay_py.so libraries will be built in the root directory of the repo.
The code needs to access the device. This can be achieved either by running the program with root privileges (so sudo is your friend) or by copying 50-usbrelay.rules to /etc/udev/rules.d, note Debian derivatives have a group 'plugdev' designed for this function. Edit 50-usbrelay.rules and substitute GROUP="plugdev" for GROUP="usbrelay"
$ sudo cp 50-usbrelay.rules /etc/udev/rules.d
$ sudo udevadm control -R
Add users that need to operate the relays to the usbrelay group
Fedora:
sudo usermod -a -G usbrelay <user name>
Debian/Ubuntu:
sudo usermod -a -G plugdev <user name>
$ sudo usbrelay --help
Usage: usbrelay [OPTION...] [ACTION...]
Control or query USB HID relays.
-d, --debug Produce debugging output
-q, --quiet Be quiet
-?, --help Give this help list
--usage Give a short usage message
-V, --version Print program version
Without ACTION, the actual state of all relays is printed to stdout.
ACTION can be one of:
RELID_N=[0|1] to switch the N-th relay off or on
RELID=NEWID to change relay ID
Report bugs to https://github.com/darrylb123/usbrelay/issues.
Running the program without arguments will display each module that matches device 16c0:05df or 0519:2018. The program can be invoked with the debug (-d) or quiet (-q) flags. The debug information is sent to stderr while the state is sent to stdout for use in scripts. The only limit to the number of these relays that can be plugged in and operated at once is the number of USB ports. Using neither the -d or -q flags just prints the state of the relays to stdout.
$ sudo usbrelay
PSUIS_1=1
PSUIS_2=0
$ sudo usbrelay -d (--debug)
Device Found
type: 16c0 05df
path: /dev/hidraw1
serial_number: PSUIS
Manufacturer: www.dcttech.com
Product: USBRelay2
Release: 100
Interface: 0
PSUIS_1=1
PSUIS_2=0
$ sudo usbrelay -q (--quiet)
$
To get the relay state
$ sudo usbrelay
PSUIS_1=1
PSUIS_2=0
To use the state in a script:
$ eval $(sudo usbrelay)
$ echo $PSUIS_2
0
To set the relay state of 1 or more modules at once:
$ sudo usbrelay PSUIS_2=0
$ sudo usbrelay PSUIS_2=1 PSUIS_1=0
$ sudo usbrelay PSUIS_2=0 PSUIS_1=1 0U70M_1=0 0U70M_2=1
Operate relay 9 to set the state of all relays together
$ sudo usbrelay PSUIS_9=0
$ sudo usbrelay PSUIS_9=1 0U70M_9=1
The path to a device can be used in lieu of the serial, this can be useful for devices with corrupted serials
$ sudo usbrelay /dev/hidraw1_1=0
Alternatively if using libusb instead of hidraw you may use the usb device path
Device Found
type: 0519 2018
path: 0001:0015:00
serial_number: A0001
Manufacturer: Ucreatefun.com
Product: HIDRelay
Release: 1
Interface: 0
Number of Relays = 9
Module_type = 2
$ sudo usbrelay 0001:0015:00_1=0
Change the serial permanently
Use the fictitious relay 0 to set the serial permanently. If you have duplicate serials, make sure only one is plugged in when you change it. Maximum of 5 character serial (A-Z0-9 only). It is probably sensible to change one module at a time to avoid serial collisions. If the serial contains characters that are not A-Z0-9 and therefore an illegal ID, you may also use the device path to set the serial as above
$ sudo usbrelay
ZXCV_1=0
ZXCV_2=0
$ sudo usbrelay ZXCV_0=ZAQ12
( or sudo usbrelay /dev/hidraw4_0=ZAQ12 )
ZXCV_1=0
ZXCV_2=0
Setting new serial
$ sudo usbrelay
ZAQ12_1=0
ZAQ12_2=0
This also optionally includes a python extension. In order to build the python extension, you must have the Python 3 development libraries installed. The docker build process will produce the python library as well.
Debian:
##Install Python3 dev package
# sudo apt install libpython3-dev python3-venv pip
# sudo pip install build
Fedora:
##Install Python3 dev package
# sudo dnf install python3-devel
# sudo dnf install python3-build
With the dependency installed, the library can be built and installed with:
##Build libusbrelay_py.so
$ cd usbrelay_py
$ make
##Install to global python
$ sudo make install
Once installed, the library can be used by any python script, assuming it is running as a user with suitable permissions per the changes to udev above.
The following is a test script included as tests/usbrelay_test.py, showing how to use the library:
import usbrelay_py
import time
# Note that a call to count() is required to enumerate the attached relays
# before attempting to operate the relays
count = usbrelay_py.board_count()
print("Count: ",count)
boards = usbrelay_py.board_details()
print("Boards: ",boards)
for board in boards:
print("Board: ",board)
relay = 1
while(relay < board[1]+1):
result = usbrelay_py.board_control(board[0],relay,1)
print("Result: ",result)
relay += 1
relay = 1
while(relay < board[1]+1):
result = usbrelay_py.board_control(board[0],relay,0)
print("Result: ",result)
relay += 1
Once the library is installed, you can run the test script in python as follows:
$ python3 test.py
It will turn on and then off every relay attached to every board on your system.
When using many relays on a system, which is shared by several users
and it is not desired to give all users access to all relays, one can
add the following line to udev rules, e.g.
/etc/udev/rules.d/50-dct-tech-usb-relay-2.rules.
SUBSYSTEMS=="usb", ATTRS{idVendor}=="16c0", ATTRS{idProduct}=="05df", IMPORT{program}="/usr/bin/usbrelay --quiet --export-id $devnode"
This ensures that subsequent rules can use relay ID stored in the ID_SERIAL environment variable to match different relays. For example giving permissions for different relays to different users can be achieved by the following rules:
SUBSYSTEMS=="usb", ATTRS{idVendor}=="16c0", ATTRS{idProduct}=="05df", ENV{ID_SERIAL}=="PSUIS", MODE="0600", OWNER="user1"
SUBSYSTEMS=="usb", ATTRS{idVendor}=="16c0", ATTRS{idProduct}=="05df", ENV{ID_SERIAL}=="0U70M", MODE="0600", OWNER="user2"
A USB relay became available that is supported by the software but with severe limitations
- Status of the relays is not available
- There is no serial so there can only be one of these modules attached to a system, unless referred to by device path. The module has a USB serial number of A0001 on every module.
- The number of relays is not available
The module has a USB device ID of 0519:2018. There are modules with 1,2,4,and 8 relays. The module accepts a request for relay 9 which turns on/off all relays. Operating the module works the same as for the DccTech modules except the serial used is A0001 Running usbrelay without arguments prints all possible relays (8) to stdout.
$ sudo usbrelay A0001_2=1 # Turns on relay 2
$ sudo usbrelay /dev/hidraw4_1=1
$ sudo usbrelay A0001_9=1 # turns on all relays
Symbolic links can be used to devices to allow physical USB ports to be referenced. The following line in a /etc/udev/rules.d file will create a symbolic link with the name of the USB port:
KERNEL=="hidraw*",KERNELS=="*-*", SYMLINK+="usbrelay%b"
The default 50-usbrelay.rules udev file creates these links for UCREATEFUN relays.
The following example has a ucreatefun usb relay plugged into a USB port and 2 dcttech relays plugged into a USB hub attached to another port:
$ ls -l /dev/hidr*
crw-------. 1 root root 243, 0 Mar 9 15:23 /dev/hidraw0
crw-------. 1 root root 243, 1 Mar 9 15:23 /dev/hidraw1
crw-------. 1 root root 243, 2 Mar 9 15:23 /dev/hidraw2
crw-------. 1 root root 243, 3 Mar 9 15:23 /dev/hidraw3
crw-------. 1 root root 243, 4 Mar 9 17:47 /dev/hidraw4
crw-------. 1 root root 243, 5 Mar 9 17:36 /dev/hidraw5
crw-------. 1 root root 243, 6 Mar 9 17:47 /dev/hidraw6
lrwxrwxrwx. 1 root root 7 Mar 9 17:47 /dev/usbrelay3-10.1:1.0 -> hidraw4
lrwxrwxrwx. 1 root root 7 Mar 9 17:47 /dev/usbrelay3-10.3:1.0 -> hidraw6
lrwxrwxrwx. 1 root root 7 Mar 9 15:23 /dev/usbrelay3-5:1.0 -> hidraw0
lrwxrwxrwx. 1 root root 7 Mar 9 15:23 /dev/usbrelay3-5:1.1 -> hidraw1
lrwxrwxrwx. 1 root root 7 Mar 9 15:23 /dev/usbrelay3-5:1.2 -> hidraw2
lrwxrwxrwx. 1 root root 7 Mar 9 15:23 /dev/usbrelay3-6:1.0 -> hidraw3
lrwxrwxrwx. 1 root root 7 Mar 9 17:36 /dev/usbrelay3-9:1.0 -> hidraw5
$ sudo usbrelay
OMG12_1=0
OMG12_2=0
QWERT_1=0
QWERT_2=0
A0001_1=-1
A0001_2=-1
A0001_3=-1
A0001_4=-1
A0001_5=-1
A0001_6=-1
A0001_7=-1
A0001_8=-1
A0001_9=-1
$ sudo usbrelay -d /dev/usbrelay3-10.1:1.0_1=1 /dev/usbrelay3-10.3:1.0_2=0 /dev/usbrelay3-9:1.0_2=0
Orig: /dev/usbrelay3-10.1:1.0_1=1, Serial: /dev/usbrelay3-10.1:1.0, Relay: 1 State: ff
Orig: /dev/husbrelay3-10.3:1.0_2=0, Serial: /dev/usbrelay3-10.3:1.0, Relay: 2 State: fd
Orig: /dev/usbrelay3-9:1.0_2=0, Serial: /dev/usbrelay3-9:1.0, Relay: 2 State: fd
Found 3 devices
Device Found
type: 16c0 05df
path: /dev/hidraw4
serial_number: ASDFG
Manufacturer: www.dcttech.com
Product: USBRelay2
Release: 100
Interface: 0
Number of Relays = 2
Module_type = 1
Device Found
type: 16c0 05df
path: /dev/hidraw6
serial_number: 48VZ7
Manufacturer: www.dcttech.com
Product: USBRelay2
Release: 100
Interface: 0
Number of Relays = 2
Module_type = 1
Device Found
type: 0519 2018
path: /dev/hidraw5
serial_number: A0001
Manufacturer: Ucreatefun.com
Product: HIDRelay
Release: 1
Interface: 0
Number of Relays = 9
Module_type = 2
Serial: /dev/usbrelay3-10.1:1.0, Relay: 1 State: ff
1 HID Serial: ASDFG Serial: /dev/usbrelay3-10.1:1.0, Relay: 1 State: ff
Serial: /dev/usbrelay3-10.3:1.0, Relay: 2 State: fd
2 HID Serial: 48VZ7 Serial: /dev/usbrelay3-10.3:1.0, Relay: 2 State: fd
Serial: /dev/usbrelay3-9:1.0, Relay: 2 State: fd
3 HID Serial: A0001 Serial: /dev/usbrelay3-9:1.0, Relay: 2 State: fd
target fd ucreate 2 f0 f0
Serial: /dev/usbrelay3-10.1:1.0, Relay: 1 State: ff --- Found
Serial: /dev/usbrelay3-10.3:1.0, Relay: 2 State: fd --- Found
Serial: /dev/husbrelay3-9:1.0, Relay: 2 State: fd --- Found
Any
MQTT support requires the successful installation of the python library described above. Check this first (with a module plugged in) by running:
sudo python3 test.py
MQTT support provides capability of using Home Assistant or nodered with usbrelay. The capability is made up of:
- usbrelayd
- usbrelay.service
- usbrelayd.conf
A python daemon using libusbrelay to connect to an MQTT server. When the daemon starts, it publishes the state of all usbrelay devices found and subscribes to command topics for each relay. To install:
Debian
sudo apt-get install python3-paho-mqtt
sudo cp usbrelayd /usr/sbin
sudo cp usbrelayd.conf /etc/usbrelayd.conf
Fedora
sudo useradd usbrelay
sudo dnf install python3-paho-mqtt
sudo cp usbrelayd /usr/sbin
sudo cp usbrelayd.conf /etc/usbrelayd.conf
Modify /etc/usbrelayd.conf to suit your circumstances.
A systemd unit for controlling and monitoring the usbrelayd daemon. The file comes configured for Fedora and needs to be modified for Debian.
Debian
Edit usbrelayd.service and change
SupplementaryGroups=usbrelay
to
SupplementaryGroups=plugdev
To install:
sudo cp usbrelayd.service /etc/systemd/system
sudo systemctl daemon-reload
A udev rule file that reacts and starts/stops the usbrelayd.service when a module is pluggedin or removed. The file should be installed with the initial installation. The file comes configured for Fedora and needs to be modified for Debian.
Debian
Edit 50-usbrelay.rules and change
GROUP="usbrelay"
to
GROUP="plugdev"
To install:
sudo cp 50-usbrelay.rules /etc/udev/rules.d
sudo udevadm control -R
After installation and configuration confirm the correct operation.
systemctl status usbrelayd
usbrelayd.service - USB Relay MQTT service
Loaded: loaded (/etc/systemd/system/usbrelayd.service; disabled; vendor preset: disabled)
Active: active (running) since Thu 2021-06-24 15:23:01 AEST; 2s ago
Main PID: 1151364 (python3)
Tasks: 1 (limit: 14159)
Memory: 14.4M
CPU: 117ms
CGroup: /system.slice/usbrelayd.service
└─1151364 /usr/bin/python3 /usr/local/sbin/usbrelayd mymqttbroker
Jun 24 15:23:01 xxx.local systemd[1]: Started USB Relay MQTT service.
Jun 24 15:23:02 xxx.local python3[1151364]: Modules Connected: 1
Jun 24 15:23:02 xxx.local python3[1151364]: State: stat/OMG12/1 OFF
Jun 24 15:23:02 xxx.local python3[1151364]: Subscribed: cmnd/OMG12/1
Jun 24 15:23:02 xxx.local python3[1151364]: State: stat/OMG12/2 OFF
Jun 24 15:23:02 xxx.local python3[1151364]: Subscribed: cmnd/OMG12/2
MQTT Topics for controlling usbrelays
- Current state: stat/SERIAL/Relay (eg stat/OMG12/1 )
- Command: cmnd/SERIAL/Relay ON/OFF (eg cmnd/OMG12/2 )
Using mosquitto client tools
mosquitto_sub -h your_mqtt_broker -t stat/OMG12/1
mosquitto_pub -h your_mqtt_broker -t cmnd/OMG12/1 -m ON
Enjoy
