STP-iS2207 Series Turbomolecular Pump 
 
MT-89E-001-C
Page 68 
5
SERIAL COMMUNICATION PROTOCOL 
5.2  Connection and setting up 
5.2.1  Signal connection 
1.  Serial Port COM1 (X3 COM1 connector) 
The serial port COM1 is available for the serial communication via RS232 or RS485. When using a 
user application, connect it to this port.   
Connect the connector X3 (D-Sub9 pin, socket type) to the PC according to Table 16. Connect only 
TxD/RxD/GND  in  the  RS232  and  D+/D–  in  the  RS485.  DO  NOT  connect  other  pins  which  are 
reserved  as  optional  use.  DO  NOT  use  a  commercially  available  straight  cable  which  all  lines are 
connected. 
However, when using the Profibus (optional accessory), serial communication function is not available 
because of the different connector pin position. (see the Instruction Manual of the Profibus) 
 
X3 
(D-Sub9 pin, socket) 
RS232  2 (TxD) 
3 (RxD) 
5 (GND) 
RS485  7 (D-) 
8 (D+) 
Reserved
1, 4, 6*, 9 
*    The pin 6 of the connector X3 outputs 5 VDC for option units. DO NOT 
connect the pin 6. Doing so may result in damage to peripheral 
equipment damage, such as PC. 
Table 16 - X3 pin position 
5  4 
3  2  1 
9  8  7  6 
 
Figure 35 - X3 connector (D-Sub9) 
Note:  The connector X3 is fitted using M2.6 screws. 
The RS232 and RS485 share the X3 COM1 port. 
When  connecting  RS232,  the  length  of  the  communication  cable  should  be  15  m  or  less.  When 
connecting RS485, refer to Section 5.2.2.