Sending data: 
The “reception done” flag, the “transmission done” flag, and the F159 (MTRN) instruction are related as 
follows: 
 
 
• Header (STX) and terminator (ETX) are automatically added to the data being transmitted. The data is 
transmitted to an external device. 
• When the F159 (MTRN) instruction is executed, the “transmission done” flag R9039 or R9049 goes off. 
• Duplex transmission is disabled while F159 (MTRN) is being executed. The “transmission done” flag 
R9039 or R9049 must be observed. 
 
 Key Point: 
• The contact numbers in parentheses refer to COM2 port.