sainsmart_relay_usb

ROS interface to SainSmart USB relay boards for automation

• 4 channel: SRD-5VDC-SL-C
  • https://www.sainsmart.com/products/4-channel-5v-usb-relay-module
  • https://www.amazon.com/dp/B009A524Z0/
• 8 channel: SRD-12VDC-SL-C
  • https://www.sainsmart.com/products/8-channel-12v-usb-relay-module
  • https://www.amazon.com/dp/B0093Y89DE/

List Devices

rosrun sainsmart_relay_usb list

Relay Node

rosrun sainsmart_relay_usb relay_node

Parameters

• serial Explicitly specify device serial number. Default <empty>
• desc Explicitly specify device description. Default <empty>

Published topics

• ready, std_msgs/Bool, true when device is connected, otherwise false, (latched topic)
• serial, std_msgs/String, serial number of the connected device (latched topic)

Subscribed topics

• relay_cmd, std_msgs/Byte, relay command (one bit per relay channel)

Troubleshooting

• Unable to connect to the device (no terminal messages)
  • Can Linux see the USB device?
    • lsusb | grep 0403:6001 * Only one executable can use a hardware device at a time. * Make sure no other running software is using the hardware. * By default, Linux USB devices have very limited permissions. Udev rules are used to modify device permissions when connected. * When installing with binaries with apt-get, the udev rules are installed automatically. * Check if this package's udev rules are installed: ls /etc/udev/rules.d/ | grep 90-SainSmartRelayUsbRules.rules or ls /lib/udev/rules.d/ | grep sainsmart-relay-usb.rules * Otherwise, follow the directions in 90-SainSmartRelayUsbRules.rules to perform a manual install. * When the board is connected to the PC and the PC is restarted, the relays will be toggled several times. This is because of the structure of the FTDI chip.