Crestron cen-com User Manual

Ethernet RS-232/422 COM Module 

Crestron CEN-COM

These two 9-pin connectors (DB9) connect to serial equipment. These bidirectional 
serial ports are used for RS-232, RS-422, or RS-485 communication.  

NOTE:  The pinout of each 9-pin port is non-standard (refer to table after this note); 
it contains RS-422 pins in addition to RS-232. This may result in a conflict with 
some equipment and therefore do not use all nine pins. Only the required pins for 
each communication type should be connected.  

NOTE:  To support RS-485, tie pin 1 (RXD-) to pin 9 (TXD-) and pin 4 (TXD+) to 
pin 6 (RXD+) in the cable, as shown below.  

 

1*

To CEN-COM

(RXD-) RS-422 Receive Data (Idles low)

2

To CEN-COM

(RXD) RS-232 Receive Data

3

From CEN-COM

(TXD) RS-232 Transmit Data

4

From CEN-COM

(TXD+) RS-422 Transmit Data (Idles high)

5

RS-232 and RS-422 Signal Common

6

To CEN-COM

(RXD+) RS-422 Receive Data (Idles high)

7

From CEN-COM

(RTS) RS-232 Request to Send

8

To CEN-COM

(CTS) RS-232 Clear to Send

9

From CEN-COM

(TXD-) RS-422 Transmit Data (Idles low)

 

*  RS-422/RS-485 are balanced signals requiring two lines plus a ground in each direction. RXD+ and 
TXD+ should idle high (going low at start of data transmission). RXD- and TXD- should idle low(going 
high at start of data transmission). If necessary, RXD+/RXD- and TXD+/TXD- may be swapped to 
maintain correct signal levels.  

This unmarked RJ45 modular connector provides Ethernet connection, thereby 
making the unit IP addressable and compatible with 10BASE-T Ethernet systems. 
The Ethernet port is the standard 10BASE-T pinout. Refer to the pinout table after 
this paragraph.  

•  Ethernet RS-232/422 COM Module: CEN-COM