RLY08 -  8 Relay Outputs 
Technical Documentation 

Serial Mode
For I2C mode click here



Serial mode selection
Serial Mode is selected by connecting the Mode pin
to ground. The Tx pin is out of the RLY08 and should be connected to Rx on your controller. The Rx pin is into the RLY08 and should be connected to Tx on your controller. These signals are 5v levels, not RS232. Do NOT connect RS232 directly to the module - you will destroy it. Use a MAX232 or equivalent to convert the RS232 levels to 5v.

Communication settings
The Serial mode operates over a link with a baud rate of 9600 bps (no parity, 1 stop bit) and 5v signals,  The RLY08 can be found at a factory default address of 1, although this is easily changed to another of eight locations - see Changing the RLY08 Address .

To send a command to the RLY08, you need to send two bytes. The first is the RLY08's address 1 (default) to 8, and then the actual command itself - see below. The RLY08 will then carry out the command and if applicable send its response. The only exception to this being the "Set relay states" command, it requires an additional required states byte to be sent immediately after the command byte. This will then set all relays to the status of the equivalent bit within the byte, with a high bit powering the relay on and a low bit turning it off. 

Commands for Serial



dec hex
90 5A Get software version - transmits a single byte back to the controller containing the software revision
91 5B

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

92 5C Set relay states - the next byte sent to the command register will set all relay 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
160 A0 1st byte in sequence to change serial address
165 A5 3rd byte in sequence to change serial address
170 AA 2nd byte in sequence to change serial address 


Changing the RLY08 Address
To change the address of the RLY08 you must have only one module connected. Write the 3 sequence commands in the correct order followed by the address. For example; to change the address of a RLY08 currently at 1 (the default shipped address) to 5, write the following to address 1; (0xA0, 0xAA, 0xA5, 0x05 ). These commands must be sent in the correct sequence to change the address, additionally, No other command may be issued in the middle of the sequence. The sequence must be sent as four separate commands to the current address of the module. i.e. 0x01, 0xA0 then 0x01, 0xAA, then 0x01, 0xA5 and finally 0x01, 0x05. When done, you should label the module with its new address, however if you do forget, just power it up without sending any commands. The RLY08 will flash its address out on the LED. One long flash followed by a number of shorter flashes indicating its address. The flashing is terminated immediately on sending a command the RLY08.

Address Long Flash Short flashes
Decimal Hex
1 01 1 0
2 02 1 1
3 03 1 2
4 04 1 3
5 05 1 4
6 06 1 5
7 07 1 6
8 08 1 7

Take care not to set more than one module to the same address, there will be a bus collision and very unpredictable results.