B&B Electronics RS-232 Digital Relay I/O 232DRIO Manual De Usuario

232DRIO-0308 Manual 

11 

 

used to specify which command will be executed by the 
controller,either the “R” or “S” character.  The set output command 
requires one argument field (for normal environments) or two 
argument fields (data and its complement for harsh environments).  
This field contains the fourth and/or fifth data byte. 

 

Command Syntax:  ! or #       0   

_   

_   _   

 

 

 

 

 

 

 

   |  

 

|   

|   

|   

|   

 

 

 

 

 

 

 

   |  

 

|   

|   

|   

| 

 

 

 

 

 

 

   |  

 

|   

|   

|     ~Data Byte 

   | 

  |  |  Data 

Byte 

       

 

 

| 

  |  Command 

Byte 

     

 

 

 

 

 

 

   |  

 

Address Byte 

       

 

Start 

of 

Message 

Byte 

 
I/O Data Bytes 

When constructing commands to manipulate output lines or 

when reading the state of the I/O lines it is necessary to know how to 
select and interpret the I/O data byte.  The three I/O lines are 
represented by one data byte.  
 

A byte represents an eight-bit binary number (11111111), 

therefore each byte can represent eight I/O lines.  Each bit is 
assigned a bit position and a weight (value).  Refer to Table 3.3.  

 

 
Input  

→ I # 

→ R # 

  7 

  6 

  5 

  4  

  3 

  2 

  1 

  0 

 80 

 40 

 20 

 10 

  8 

  4 

  2 

  1 

Decimal Weight  128    64 

 32 

 16 

  8 

  4 

  2 

  1 

 

 

 

 

To set an output to a HIGH state the corresponding bit position 

must be set to a "1".  Conversely to set an output LOW the 
corresponding bit position must be set to a "0".  When reading I/O 
lines, any bit set to a  "0" indicates the corresponding  I/O line is in 
the LOW state and any bit set to a "1" indicates the corresponding 
I/O line is in the HIGH state.