USB-OPTO-RLY88, 8 optically Isolated Inputs, 8 Relay Outputs 
Technical Documentation 

Overview
The USB-OPTO-RLY88 provides eight optically isolated inputs and eight volt free contact relay outputs with a current rating of up to 1Amp each. It is powered from any standard USB bus and has an exceptionally low maximum current consumption of approx. 90mA with all relays on. The relays are SPCO (Single Pole Change Over) types. The normally open, normally closed and common pins are all available on the screw terminals.

Specification
USB - Standard type B receptacle.
Inputs - Absolute Max. 30v DC, Operational 4.5v to 27v DC
Outputs - Relay Contacts, see power graph below

LED Indication
Each of the eight input channels has a Green LED to indicate the input status.
Each relay output has a Red LED to indicate the relay status.
Also power status is indicated with an LED driven from the USB supply.

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.

Which COM port?
Plug in the USB-OPTO-RLY88 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 "Properties->Hardware->Device Manager". Now scroll down and open the "Ports (COM & LPT)" tab. You should see the USB serial port listed - COM5 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 default will probably be set up for 9600 baud, 8 data bits, no parity and one stop bits, but what ever it is just ignore it. These settings are not actually used because we have a full 12Mbits USB connection right into the heart of the processor.

Commands
The USB-OPTO-RLY88 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-OPTO-RLY88 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. 

Command

Action
dec hex
17 11 Returns channel 1 state as 1 byte, where 255 indicates input is powered and 0 indicates it is not.
18 12 Returns channel 2 state as 1 byte, where 255 indicates input is powered and 0 indicates it is not.
19 13 Returns channel 3 state as 1 byte, where 255 indicates input is powered and 0 indicates it is not.
20 14 Returns channel 4 state as 1 byte, where 255 indicates input is powered and 0 indicates it is not.
21 15 Returns channel 5 state as 1 byte, where 255 indicates input is powered and 0 indicates it is not.
22 16 Returns channel 6 state as 1 byte, where 255 indicates input is powered and 0 indicates it is not.
23 17 Returns channel 7 state as 1 byte, where 255 indicates input is powered and 0 indicates it is not.
24 18 Returns channel 8 state as 1 byte, where 255 indicates input is powered and 0 indicates it is not.
25 19 Sends 1 byte back. Individual bits indicate input status of each channel, a 1 indicating powered input
26 1A Sends 8 bytes back. First byte is channel 1 as per command 0x11 above. Last byte is channel 8.
     
56 38 Returns 8 ASCII characters. This is an 8-digit globally unique identifier. No two modules will share this. 
     
90 5A Get software version - returns 2 bytes, the first being the Module ID which is 12, 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
92 5C Set relay states - the next single byte will set all relays states, All on = 255 (11111111) All off = 0
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

Opto Input Schematic

Board dimensions

  

Test program and example source code
To get the USB-OPTO-RLY88 up and running in the minimum amount of time we have put together an example program to demonstrate the functionality of the module.  

The test program is available built and ready to install here OptoRelayTest or as C# source code here OptoRelaySource