CHAPTER 1: INSTALLING THE PCI-AC48 ADAPTER CARD
PCI-AC48 User’s Guide
11
11
Wiring for RS-485 2-Wire (Two Serial Ports)
The following wiring diagram assumes that you are using the PCI-AC48 for two 2-wire ports with no
interrupts. (If you are using interrupts, see
page 20
.)
Wiring for RS-485 4-Wire (One Serial Port)
The following diagram assumes that you are using the PCI-AC48 for one 4-wire port with no
interrupts. (If you are using interrupts, see
page 20
.)
In 4-wire mode, Port A is TX and Port B is RX. It is easiest to jumper the commons and wire them
both at the same time
Recommended Serial Cable Specifications
RS-485 serial lines require twisted pair cable with a maximum cable length of 3,000 feet (915 m). The
recommended cable type is two twisted pairs of 24 gauge conductors with a shield. Nominal
impedance is 100 ohms and capacitance is 12.5 picofarads per foot.
Typical manufacturer part numbers are:
•
Manhattan Electric Cable: M3475
Serial Port A
Serial Port B
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
TX/R
X +
TX/R
X –
C
omm
TX/R
X +
TX/R
X –
C
omm
Please note the following equivalents for wiring
.
Opto 22
Other
Vendors
Optomux
TX/RX +
TX/RX(B)
TO/FO +
TX/RX –
TX/RX(A)
TO/FO –
Port A
Port B
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
TX
+
TX
–
C
omm
RX
+
RX
–
C
omm
Please note the following equivalents for wiring
.
Opto 22
Other
Vendors
Optomux
TX +
TX(B)
TO +
TX –
TX(A)
TO –
RX +
RX(B)
FO +
RX –
RX(A)
FO –
