Antona Corporation
13
(818)783-4299
each be assigned a unique ‘device code’. Check with the specific equipment’s
User’s Manual
for setting this, along with protocol, baudrate, character length, parity and stop bits to match your
PC’s application software.
Data Direction Jumpers
When shipped the Antona adapter is set for a MASTER interface. Connector pinouts are
shown in this manual for both MASTER and SERVER mode, so be sure you are looking at the
correct table. You may also want to open the Antona adapter up and verify the jumpers JP5/6
are set for the mode you desire. All 4 jumpers should be installed, they each represent one of
the 4 signals being transmitted and received. The Appendix C Schematic shows how and where
these jumpers are located. On the ANC-6185T, terminal block version, there should be no
reason to change the JP5/6 positions as that adapter has each pin’s function available via a
discrete wiring connection the user places into the terminal block.
Signal Control Jumpers
There are three main jumpers – JP1/2/3 that control the operation of the signal switching on the
ANC-6185 for transmit and receive enabling. Double check that you have set the jumpers
correctly for your application. All three jumpers must be installed for the adapter to work
properly and it is possible to have one mis-setting cause the adapter to appear non-operational.
Check the adapter jumper settings against the Appendix C schematic (left hand side). As a
baseline, restore all jumper settings to the factory defaults shown on the schematic.
Cable Termination
Reflected signal produced by cabling that is not terminated properly will cause data
transmission errors. A terminated cable matched to the impedance of the cable wire produces
the maximum signal transfer and dampens the ringing of a reflected signal. Cable with a
nominal 120 ohm impedance will work the best (low cost UTP CAT-5 works good).
If you are using the adapter to interface with one piece of equipment, a short cable run (under
150 feet), in an electrically ‘clean’ environment (like an office) then you probably do not need the
cable to be terminated. If on the other hand you are using the ANC-6185 to interface with 2 or
more RS-485 devices in an industrial environment with hundreds of feet of cable – terminating
both ends of the cable at the end points would be required. The adapter has a jumper enabled
120 ohm resister (JP4) that takes care of the adapter end of the cable. The user must connect a
similar resister at the far end of the cable run. An unterminated cable will not work generally with
long cable runs, and baudrates above 2400 baud
. Externally powering the adapter for such
an application would be required.
The best way to determine if termination is causing your
interface not to work is to just enable the ANC-6185 terminating resister and install a 120 ohm
resister onto the last piece of RS-485 equipment on the cable. Check also, that you have not
over-terminated the cable by having more than two resisters installed other than one at each end
of the cable run. Access one end of the cable and use a multimeter set to the 200 ohm scale.
You should measure about 60 ohms if there are two 120 ohm resisters in parallel across the
cable. If you are using multiple Antona adapter’s, only one at each end of the cable should have
JP4 enabled. Likewise, check any other piece(s) of equipment on the cable to make sure, if they
contain termination resisters, that only one of them is enabled at the end of the cable.
Powering
Be sure that the RTS and/or DTR line on your RS232 interface are high. Those lines power the
Antona adapter (like a mouse interface) if you are not connecting an external DC power source
on the appropriate pins of the terminal block or RJ-45 connector. Some portable computers just
do not have enough power to run the adapter and/or the RS422/485 piece of equipment you are