SimpleComTools, LLC COM1000 – User Manual
SimpleComTools, LLC 9
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 Serial/IP from
Tactical Software (www.tacticalsoftware.com), TCP-COM from TalTech (www.taltech.com) and VSP from
HW Group (www.hwgroup.cz). Simple Com Tools also offers a similar application called Virtual-COM UDP
that provide Virtual Com Port to UDP redirection only (www.simplecomtools.com/virtualcomudp.html)
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 show in the diagram at right.
