3.  Instruction  Set 
 
ASCII mode (M1143 = OFF)   
When X0 = ON, MODRW instruction executes the function specified by Function Code H0F. 
PLC1  PLC2, PLC sends: “ 01 0F 0500 0010 02 3412 93 ”   
PLC2  PLC1, PLC receives: “ 01 0F 0500 0010 DB ” 
Registers for data to be sent (sending messages)   
Device address: ADR (1,0)   
Control parameter: CMD (1,0)   
Data Address 
Number of Data (count by bit) 
Byte Count 
 
Data contents 
1234H   
Content of register D0 
Checksum: LRC CHK (0,1)   
 
Registers for received data (responding messages) 
   
Data Address 
Number of Data(count by bit)