Manual OC32/NG
VPEB
Control your Miniature World
Page 26 of 48
Version 1.0 – December 15
th
, 2017
2017 Leon van Perlo
If you connect the OC32 directly to the COM-port of a PC, then you need to obtain the
RS232 TxD signal from the COM-port. You can buy a serial cable for this, but it is cheaper
and most likely easier to manufacture one yourself. The case is that you only require 2 wires
from the COM-port of your PC.
Buy a 9 pin subD female connector, possibly with a cover, and a piece of signal cable with at
least 2 wires. You can very conveniently use a piece of cable with shielding and conducting
core, a sort of very thin coax cable that is normally used for connecting audio equipment.
Solder one wire to pin 5 of the subD connector (this will be the GND) and the other wire to
pin 3 (this will be the TxD). If you use a shielded cable with conducting core, you solder the
shield to pin 5 and the core to pin 3.
To the other side of the cable, you connect the GND wire (or shield) to the GND of your
layout. The TxD signal wire you connect to pin 4 of K1 on the OC32 (green wire in fig 16).
Fig 16: Connecting RS232 communication to the PC
If you are using a USB-RS232 converter, then the pin layout of its 9-pin connector should
be identical to that of a normal PC COM-port and the whole game will work as described
above. The only difference is that there is a USB cable between your COM-port and the PC.
In most cases you have to install drivers as well to make the USB-serial converter work.
Have a look at the manual of your USB-serial converter for this.
If you have multiple OC32 modules on an RS232 bus, then you can connect them in parallel.
Just interconnect the GND (pin 2) and data (pin 4) of all modules. You can do that in a bus
or star configuration. Of course you can also interconnect PWR (pin 1), if all modules share
the same power supply.
Note that the fan-out of a standard com-port, and especially the com port on a USB-Serial
converter, is limited and therefore there may be a limitation to the number of modules you
can connect this way. Up to 10 units should normally work fine. If you want to connect more
modules than your com-port can drive, you need to use a signal amplifier.
5.5
DCC control
For operational control, the OC32 can receive and process DCC signals, as long as the
OC32 module is provided with a DCC interface
DCC is a 2-wire signal. Connect the DCC signal of your digital system to the DCC interface
of the OC32. DCC is polarity insensitive. This means that it doesn’t matter whether you
swap the 2 wires of the DCC interface.
How to obtain a DCC signal from your digital system can be found in the documentation of
your digital system. It might be that there are multiple DCC connections on your digital
system. Just keep the following in mind:
•
If possible, use a connection that is not directly connected to the track. If it does, short
circuits and interference might influence the operation of accessory decoders like the
OC32 is.
1
5
6
9
9subD-female
RS232 TxD
GND
1
5
6
9
9subD-female
1
5
6
9
9subD-female
RS232 TxD
GND
Control your Miniature World
VPEB
Manual OC32/NG
2017 Leon van Perlo
Version 1.0 – December 15
th
, 2017
Page 23 of 48
5.3.5
Connecting multiple OC32/NG’s to a PC – Option 1
The easiest way to connect multiple modules is to use RJ45 cables. Since the U485 has no
RJ45 connector you need to connect the U485 to the first OC32/NG module as in figure
13.
Now plug an RJ45 cable in one of the RJ45 sockets of that first OC32/NG and plug the
other end in an RJ45 socket of the second OC32/NG. If you have more modules, plug
another cable in the free socket of the second OC32/NG and plug the other end in module 3.
Continue with this process to the last module.
Note:
Only the U485 and the last OC32/NG module shall
have the terminator active.
On the OC32/NG to which you have connected the
U485, only one RJ45 may be used.
Fig 13: Connecting multiple OC32/NG’s with RJ45 cables
Address
RS485 terminator NOT activated
Address
Address
RS485 terminator NOT activated
RS485 terminator activated
U485
PC
RS485 terminator activated
