When 
extendable racks are used, the bus X must be fitted with a line terminator at each end.           
 
           
           
A line terminator is made up of a 9-pin SUB D connector and a cover containing the adaptation components. It is mounted on the 9-pin SUB D 9 connector belonging to the extendable rack at the end of the line.           
Illustration:           
TSX TLYEX line terminations are sold in twos and marked 
A/ and 
/B. The bus must be fitted with a terminator 
A/ at one end and a terminator 
/B at the other end in no 
predefined order.