NPB-2X-RS485 OPTION CARD
95-7778—01
2
Preparation
Examine the component side of the option card to locate the
bias resistor jumper pins. See Fig. 2. You may wish to enable
biasing for either (or both) RS-485 ports before mounting the
card.
Fig. 2. Jumpers to enable RS-485 Bias resistors.
NOTE: You cannot reach these jumpers when the card is
installed.
In general, only one device on an RS-485 trunk should be
biased. Otherwise, undue loading of the circuit may result,
with fewer devices supported.
NOTE: RS-485 bias resistors are different than termination
resistors. They are externally installed at the two
physical ends of a daisy chained RS-485 trunk
across the + and – terminals. Termination resistors
are typically 100 or 120 ohm value resistors.
Whenever termination resistors are used, RS-485
biasing is typically required.
To enable biasing, install the two 2-pin jumper blocks
(provided in this package) on that port’s jumper header, as
shown in Fig. 2. To turn off biasing, remove both 2-pin jumper
blocks from that port’s header.
NOTE: The factory-shipped state is with the jumper blocks
removed.
Installing jumpers to enable biasing adds two onboard 3.3K
ohm resistors into an RS-485 port’s circuit:
• from RS-485 positive (+) to 5V.
• from RS-485 negative (–) to Ground.
Biasing can improve RS-485 communications by eliminating
indeterminate idle states.
MOUNTING
WARNING
Power to the controller must be OFF when
installing or removing option cards, or damage
will occur!
Also, you must be very careful to plug any option card
into its connector properly (pins aligned).
Mount the NPB-2X-RS485 option card in either of the option
card slots of the controller, as needed. Note the WEB/CP-202/
602-XPR series has only one option card slot.
Mounting the NPB-2X-RS485 option
card on a controller
Refer to the “Preparation” section on this page for details
about RS-485 resistor biasing.
See “COM Port Usage” on page 3 for details about COM port
assignments for the controller.
1.
Remove power from the controller. Wait for all LEDs on
the unit to be Off.
2.
Remove the controller cover or covers (WEB/CP-202/
602-XPR).
For all but the WEB/CP-202/602-XPR, press in the four
tabs on both ends of the unit, and lift the cover off.
NOTE: If accessory modules are plugged into the con-
troller, you may need to slide them away from
the unit to get to the cover tabs.
3.
For the WEB/CP-202/602-XPR, first remove the right
cover, then the left cover, retaining the two screws that
secure each cover.
4.
For all but the WEB/CP-202/602-XPR, remove the
battery and bracket assembly by taking out the screws
holding it in place, setting the screws aside for later.
Unplug the battery from the connector on the controller.
See Fig. 3 on page 2 for an exploded view.
Fig. 3. Remove battery assembly.
5.
Remove the blanking end plate for the slot you are
installing the option card into.
(Retain the blanking end plate in case the option card
must be removed at a later date.)
ENABLE
BIAS
SCREENED DIAGRAM SHOWS HOW TO ENABLE THE BIAS
RESISTORS BY INSERTING TWO JUMPER BLOCKS
OVER EACH SET OF PINS.
BIAS JUMPER BLOCKS IN PLACE; TWO FOR EACH PORT.
1
1
2
2
TO BIAS
THIS PORT
TO BIAS
THIS PORT
Screws (4)
Option
Slot 2
Area
WEB/CP-201/600/
700
Blanking
End
Plate
Battery
Assembly
(includes
cable and
bracket)
Unplug battery here
Option
Slot 1
Area
