6-30
Interfaces
The cable diagrams provide wiring examples for both 9 pin and 25 pin serial ports from an IBM compatible
personal computer to the drive. RS-232 pin-outs vary between computer manufacturers. Check the hard-
ware reference manual of your machine to ensure correct signal connections between the computer and
the drive.
Four Wire RS-485 Connections
The OMNIDRIVEs use a variation of the RS-485 standard, known as four wire RS-485. Four wire RS-
485 uses one differential signal for host to drive transmissions, and another differential signal for drive
to host transmissions. (The RS-485 standard specifies a single differential signal for transmissions in both
directions.)
The four wire RS-485 configuration also allows the host to use a RS-422 type interface. Because the host
is driving multiple receivers and receiving from multiple transmitters, RS-422 is limited to multiple axes
connections with 10 or less drives. The figure below summarizes the four wire RS-485, RS-422, and RS-
485 standards.
NOTE:
The Scan Port for Attached Drives option in the Drive Select
window of OMNI LINK will identify any attached drives. If a drive is
identified, but cannot be communicated with, the Baud Rate selection
must be modified.
Intro
Four Wire RS-485
Differential
4 Wires
2 Signal Pairs
1 to 32 Transmitters
1 to 32 Receivers
Intro
RS-422
Differential
4 Wires
2 Signal Pairs
1 Transmitter
1 to 10 Receivers
Intro
RS-485 Standard
Differential
2 Wires
1 Signal Pair
1 to 32 Transmitters
1 to 32 Receivers
NOTE:
Not applicable
to OMNIDRIVEs
F
IGURE
6.40
RS-485/RS-422 Communication Comparison
1
2
32
1
2
10
1
2
32
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