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16Amp, 8 Channel USB Relay Module

Original price €80,73 - Original price €80,73
Original price
€80,73 - €80,73
Current price €80,73

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The USB-RLY16 provides eight volt free contact relay outputs with a current rating of up to 16Amp each. The processor is powered and instructed by any standard USB bus and the relay power is obtained by the DC power input adapter. The DC input jack is 2.1mm with positive core polarity, DC supplies are required to supply at least 500mA at 12vdc. The relays are SPCO (Single Pole Change Over) types. The normally open, normally closed and common pins are all available on the screw terminals.

LED indication
The USB-RLY16 provides a red LED mounted immediately next to each relay to indicate whether it is in a powered state (LED on), there is also two LED's which will flash with USB transactions to and from the module, green indicating reception of data from the PC and yellow the transmission of data to the PC. Finally there is red power LED mounted near to the USB connector.

Relay power rating
If the contact load voltage and current of the relay are in the region enclosed by the solid and dotted lines in the figure below, the relay can perform stable switching operation. If the relay is used at a voltage or current exceeding this region, the life of the contacts may be significantly shortened.

load type Typical applications Rating Max DC load capacity

AC1 Not inductive or
slightly inductive loads
16A @ 250V AC
AC15 Control of
electromagnetic load
3A @ 120V AC
1.5A @ 240V AC
AC3 Control of motor 750W
DC1 Not inductive or
slightly inductive loads
16A @ 24V DC
DC13 Control of electromagnetic
0.22A @ 120V DC
0.1A @ 250V DC

A full datasheet for the relays used on the RLY16 is here: RM85 datasheet

First Step - Get The Drivers
The USB-RLY16 module uses the FTDI FT232R USB chip to handle all the USB protocols. The documentation provided by FTDI is very complete, and is not duplicated here. Before using the USB-RLY16, you will need to install FTDI's Virtual COM Port (VCP) Drivers. These drivers appear to the system as an extra Com Port (in addition to any existing hardware Com Ports). Application software accesses the USB device in the same way as it would access a standard Windows Com Port using the Windows VCOMM API calls or by using a Com Port Library. Drivers are available for Windows, Apple, Linux and Open BSD systems directly from the FTDI website . You should get and install the drivers now, before you connect the USB-RLY16 to your computer. The Drivers page is here .

Which COM port?
After installing the drivers, and plugging in the USB-RLY16 module to a spare USB port, you will want to know which COM port it has been assigned to. This will vary from system to system depending on how many COM ports you currently have installed. To find out where it is, right click on your "My Computer" desktop icon and select the "Device Manager" tab. Now scroll down and open the "Ports (COM & LPT)" tab. You should see the USB serial port listed - COM2 in the example below. If you want to change the COM port number - just right click on it, select properties, select advanced and select the COM port number from the available list. The COM port should be set up for 19200 baud, 8 data bits, no parity and two stop bits.

The USB-RLY16 operates with an easy to use command set as described in the table below. Most commands are only a single byte and if applicable the USB-RLY16 will automatically send its response. The only exception to this being the "Set relay states" command which requires and additional desired states byte to be sent immediately after the command byte.



dec hex
90 5A Get software version - returns 2 bytes, the first being the Module ID which is 9, followed by the software version
91 5B

Get relay states - sends a single byte back to the controller, bit high meaning the corresponding relay is powered

ninety two 5C Set relay states - the next single byte will set all relays states, All on = 255 (11111111) All off = 0
93 5D Get DC input voltage - returns relay supply voltage as byte, 125 being 12.5V DC
100 64 All relays on
101 65 Turn relay 1 on
102 66 Turn relay 2 on
103 67 Turn relay 3 on
104 68 Turn relay 4 on
105 69 Turn relay 5 on
106 6A Turn relay 6 on
107 6B Turn relay 7 on
108 6C Turn relay 8 on
110 6E All relays off
111 6F Turn relay 1 off
112 70 Turn relay 2 off
113 71 Turn relay 3 off
114 72 Turn relay 4 off
115 73 Turn relay 5 off
116 74 Turn relay 6 off
117 75 Turn relay 7 off
118 76 Turn relay 8 off

Board dimensions

Test program and example source code

To get the USB-RLY16 up and running in the minimum amount of time we have put together an example program to demonstrate the functionality of the module.

Visual studio express examples

Visual C# express
The test program is available as a visual C# express built exe file here USB RLY16 TEST or as visual C# express project here USB-RLY16 .

Visual basic express
The test program is available as a visual basic express built exe file here USB RLY16VB or as visual basic express project here .

Visual studio express is provided free from Microsoft here: