Instruction manual

5150
Digital
C o m m u n i c a t i o n s
short as possible; however, the line may be daisy-chained at
each controller. The polarity of the line is important and each
device will specify an “A” (+) and “B” (-) connection.
Note: Call factory for a
recommended RS485
converter.
Figure 19. Wiring
diagram for digital
communications.
Two communication
options are available
which allow interfacing
to remote devices
utilizing the most
common industry
standards, RS232 and
RS485.
WARNING
Signal ground only.
Grounding to frame
may damage the
controller and void
warranty.
Digital
C o m m u n i c a t i o n s
RS232
This method allows bidirectional data transfer via a three-
conductor cable consisting of signal ground, receive input
and transmit output. It is recommended for communication
distances less than fifty feet between the computer terminal
and the instrument. Note: Multiple instruments cannot be
connected to the same port.
The RS232 port is optically isolated to eliminate ground loop
problems. Typically, “Data Out” of the computer/terminal con-
nects to the “RCV” terminal. “Data In” connects to the “XMT”
terminal. If shielded cable is used, it should be connected to
the frame ground at one end only. Signal ground is to be con-
nected at appropriate ground terminals (refer to wiring dia-
gram, page 51).
RS485
The RS485 multipoint capability allows up to 32 controllers to
be connected together in a half-duplex network or up to 100
controllers with an appropriate communications repeater. This
method allows bidirectional data transfer over a shielded
twisted pair cable. The twisted pair cable is a transmission
line; therefore, terminating resistors are required at the most
distant ends of the line to minimize reflections (typically 60
ohms from each line to signal ground). The RS485 circuit is
fully optically isolated, eliminating ground loop problems.
Parallel drops from the transmission lines should be kept as