3com S7906E Guide D’Installation Rapide

 

3-13 

The connection procedure of the RS-232 port and that of the RS-485 port are shown respectively as 

follows (taking the S7902E using the PSE2500-A as an example): 

If the RS-232 port is used, use an 8-core shielded cable. One end of the cable is a crimped RJ-45 

connector, which is connected to the RS-232 COM port on the rear panel of the S7902E; the other end 

is attached with a DB-9 female connector and can be connected to the RS-232 port of PSE2500-A. The 

COM cable is similar to the console cable. For details, see 

. 

If the RS-485 port is used, use a straight through cable to connect the COM port with the RS-485 port on 

the PSE2500-A.  

The PoE monitoring port on the PSR1400-D is an RS-485 port. You can select a proper connection 

method for the RS-485 port according to the type of the PoE monitoring port on the external power 

module. 

 

When the S7900E series adopt only the –48 V DC power, but no external PoE power supply, it is 

unnecessary to connect the COM port. 

 

10Base-T/100Base-TX and 1000Base-T ports of the S7900E series use RJ-45 connectors, support 

MDI/MDIX auto-sensing, and adopt category-5 cables. The following figure illustrates the appearance 

and pinouts of RJ-45 connector. 

Figure 3-15 RJ-45 connector 

 

 

Table 3-2 RJ-45 MDI interface pinouts  

1 Tx+ 

Send 

data 

BIDA+ 

Bi-directional data cable A+ 

2 Tx- 

Send 

data 

BIDA- 

Bi-directional data cable A- 

3 Rx+  Receive 

data 

BIDB+ 

Bi-directional data cable B+