RS485 Configuration and Wiring
The COM1000 RS485 port is an unaddressed transparent interface designed to support
any RS-485 equipment. It supports both Full and Half-Duplex communications, so it
can be used to interface a single device or a multi-drop network of devices.

Applications
The COM1000 RS485-port can be configured to perform a number of applications,
including acting as a UDP or TCP device server or client, data redirecting via SMTP
or FTP, and data arrival event logging. The choice of applications is detailed in
the COM1000 Configuration Utility section under the RS485 tab.

TCP/UDP Servers
The most common use for the RS485 port is as a TCP or UDP device server. In this
application, the COM1000 provides the ability to reach RS485 connected devices or
device networks from any remote IP host via a standard RAW TCP or UDP socket. Since
the COM1000 is a transparent IP to serial bridge, there are no limitations on the
data protocol. Any ASCII or Binary protocol will be passed seamlessly to the end
device.

Communication Drivers
The COM1000 IP-to-serial application is a raw socket connection. Therefore there
are no driver requirements to establish your connection. As long as your host-end
application has the ability to encapsulate the ASCII or Binary data stream into a
TCP or UDP packet, you will be able to make the connection. If you host end
application does not have that ability, you may need to employ the use of a serial
to IP COM Port Redirector.

The purpose of the redirector is to make the virtual COM port exhibit behavior that
closely resembles that of a "real" COM port, i.e., a COM port driver for local
serial port hardware. A virtual COM port itself is a relatively simple software
mechanism that can be implemented by driver software similar to that of a
conventional COM port driver. The redirector will typically permit creation of many
(at least 256) virtual COM ports, and provide the ability to assign or bind a remote
IP address of a device server to that virtual port. This, in order to reach a remote
device, the host application simply opens the virtual com port associated with that
remote device and the connection is automatically established.

There are a number of such applications on the market, available from companies such
as NetSerial from PC Micro (www.pcmicro.com), TCP-COM from PC Micro (www.pcmicro.com)
and VSP from HW Group (www.hwgroup.cz). We also offer a similar application called
Virtual-COM UDP that provide Virtual Com Port to UDP redirection only.

Port Configuration
The COM1000 is capable of supporting a variety of baud rate options, ranging from
1200 – 115200kbps. In addition, the 485 interface supports both full-duplex and half-
duplex installations. By default, the COM1000 is setup in Half-duplex mode. In order
to support full-duplex, the RS485 Mode register needs to be set (RS485Mode=1).
See the RS485 command list for more details on configuring the 485 port options.

Wiring
The COM1000 RS485 interface has 5 terminals:
COMMON (GND), TX+/TX- and RX+ and RX-.
When used in full-duplex mode, wiring should
follow the specifications set forth by the
equipment vendor. The RS485mode selection
needs to be set to (1). When used in half-
duplex mode, the COM1000 will need to have
the TX+/RX+ and TX-/RX- terminals jumpered
as shown to the right.