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4.2.2 RS-422 Sub-Channel Connections
Similar to the Model 305X, the Models 305X-422 Series multiplex
and de-multiplex signals from four or six, or eight EIA-422 devices.
EIA-422 devices may use D-Sub 25, D-Sub-9, RJ-45 or another
connector type to transmit and receive data and operate flow control..
As with the Model 305X, you will need an adapter cable to make the
proper connections. Figure 5, below, shows the pin assignments on the
RJ-45 sub-channel modular jack on the 305X-422 Series.
The diagrams below show the pinning of two RS-422 patch cables:
DB-25 (RS-530) to RJ-45 and DB-9 (RS-449) to RJ-45. Because RS-
422 is a balanced interface, you should
always use twisted pair wire
for
RS-422 cable (See Appendix B). Using low capacitance twisted pair
cable between 19 and 24 AWG, you should be able to attain sub-
channel distances up to 1000 ft. Please be careful to observe the
correct wire pairing as shown below.
RS-530 (422) Model 305X-422
DB-25 Pin No. RJ-45 Pin No.
2 (XMT+) 6 (RCV+)
14 (XMT-) 2 (RCV-)
3 (RCV+) 5 (XMT+)
16 (RCV-) 3 (XMT-)
RS-449 (422) Model 305X-422
DB-9 Pin No. RJ-45 Pin No.
3 (XMT+) 6 (RCV+)
9 (XMT-) 2 (RCV-)
4 (RCV+) 5 (XMT+)
6 (RCV-) 3 (XMT-)
4.2.3 Extending RS-232 Sub-Channel Distances
You can also multiplex signals from sub-channel devices that are
located
more than 50 feet
away from the Model 305X. Use a Patton
Model 305X-422 with a Patton Model 222N RS-232 to RS-422 converter
(see Appendix C for specific model numbers).
As Figure 6 below illustrates, the Model 222N replaces the modular
to D-shell converter at the device end. This set-up allows sub-channel
cable runs up to 1000 feet over two twisted pair wire. Call Patton
Technical Support at for more information about the Model 222N.
4.2.4 Flow Control Requirements
All versions of the 305X Series accomodate flow control. Flow
control is a method whereby devices that process data more slowly (i.e.
printers) can request faster processing devices (i.e. PCs) to temporarily
stop and then restart data transmission. This gives a slower processing
device the ability to clear its receive buffer to accept additonal data. All
versions of Model 305X operate with software flow control. Models
3054AR and 3056AR may also operate with RTS/CTS (hardware) flow
control.
Software Flow Control
The Model 305X Series is transparent to software flow control
method on the sub-channel ports. Both sub-channel devices must be
set to XON/XOFF or ACK/NAK or any other end-to-end software flow
control method. The Model 305X simply passes the software flow
control parameters through from end-to-end without modification.
(continued)
7 8
CHANNELS TESTS CHANNELS TESTS
Figure 6. RS-232 sub-channel distance extension
Model 222N
1 Mile on UTP
1000 ft on UTP
Model 222N
1 no connection
2 (RCV-) to 305X-422
3 (XMT-) from 305X-422
4 (SG) Signal Ground
5 (XMT+) from 305X-422
6 (RCV+) to 305X-422
7 no connection
8 no connection
1
2
3
4
5
6
7
8
Figure 5: Model 305X-422 RJ-45 Sub-Channel Pin Numbers