Impulse 1104 User Manual
DIN485+
Users Manual
Part Number 1104
Sealevel Systems, Inc. Telephone: 864.843.4343
PO Box 830 Fax: 864.843.3067
Liberty, SC 29657 USA www.sealevel.com
Contents
INTRODUCTION .....................................................................................................................................................1
OVERVIEW................................................................................................................................................................1
WHAT’S INCLUDED...................................................................................................................................................1
FACTORY DEFAULT SETTINGS ..................................................................................................................................1
CARD SETUP............................................................................................................................................................2
RS-485 ENABLE MODES ..........................................................................................................................................2
LINE TERMINATION AND RECEIVER ECHO OFF/ON...................................................................................................4
ELECTRICAL INTERFACE EXAMPLES (DIP SWITCH SW2) .........................................................................................5
OPERATING SYSTEM INSTALLATION (FOR WINDOWS USERS) .............................................................6
RS-422/RS-485 FOUR WIRE MASTER/RS-485 TWO WIRE AUTO MODE INSTALLATION..........................................6
RS-485 TWO-WIRE AND RS-485 FOUR-WIRE SLAVE INSTALLATION.......................................................................6
OTHER OPERATING SYSTEMS ...................................................................................................................................8
PHYSICAL INSTALLATION..........................................................................................................................................8
TECHNICAL DESCRIPTION.................................................................................................................................9
CONNECTOR PIN ASSIGNMENTS ...............................................................................................................................9
Power/RS-232 Pin Assignments (6 Position Screw Terminal) ............................................................................9
RS-422/485 Pin Assignments (6 Position Screw Terminal).................................................................................9
SPECIFICATIONS .................................................................................................................................................10
ENVIRONMENTAL SPECIFICATIONS .........................................................................................................................10
MANUFACTURING...................................................................................................................................................10
PHYSICAL DIMENSIONS ..........................................................................................................................................10
APPENDIX A - TROUBLESHOOTING ..............................................................................................................11
APPENDIX B - HOW TO GET ASSISTANCE....................................................................................................12
APPENDIX C - ELECTRICAL INTERFACE .....................................................................................................13
RS-232...................................................................................................................................................................13
RS-422...................................................................................................................................................................13
RS-485...................................................................................................................................................................13
APPENDIX D - ASYNCHRONOUS COMMUNICATIONS..............................................................................14
APPENDIX E - SILK-SCREEN.............................................................................................................................15
APPENDIX F - COMPLIANCE NOTICES .........................................................................................................16
FEDERAL COMMUNICATIONS COMMISSION STATEMENT ........................................................................................16
EMC DIRECTIVE STATEMENT ................................................................................................................................16
WARRANTY ...........................................................................................................................................................17
© Sealevel Systems, Inc.
SL9137 Revision 7/2006
Sealevel Systems, Incorporated. All rights reserved.
Introduction
Introduction
Overview
The Sealevel Systems DIN485+ is a DIN rail mountable single channel RS-232 to RS-422/485 asynchronous
converter. It provides one field selectable RS-422/485 serial port supporting asynchronous data rates up to
115.2K bps. The DIN485+ is self-powered allowing it to correctly drive multi-drop RS-485 networks.
Configure the port as RS-422 for long distance device connections up to 4000ft. where noise immunity and high data
integrity are essential. Select RS-485 and capture data from multiple peripherals in an RS-485 multi-drop network.
Up to 31 RS-485 devices can be connected to automate your data collection.
In RS-422 and RS-485 Auto modes, the card works seamlessly with the standard operating system serial driver. Two
additional methods are provided to control the communication line in RS-485 mode. The “Data Enable” mode uses
the transmitted data to enable the transmitter and requires no software drivers. This mode has limitations that will be
discussed in more detail later. The “RTS Enable” mode uses the UART modem control signal RTS to control the
communication line and requires the Sealevel Systems’ serial driver.
What’s Included
The DIN485+ is shipped with the following items. If any of these items is missing or damaged, contact the supplier.
• DIN485+ Serial I/O Adapter
• Sealevel Software
Factory Default Settings
The DIN485+ factory default settings are as follows:
Port # Electrical Specification
Port 1 RS-422
To install the DIN485+ using factory default settings, refer to Installation.
For your reference, record installed DIN485+ settings below:
Port # Electrical Specification
Port 1
Sealevel Systems DIN485+ Page 1
Card Setup
Card Setup
RS-485 Enable Modes
RS-485 is ideal for multi-drop or network environments. RS-485 requires a tri-state driver that will allow the
electrical presence of the driver to be removed from the line. The driver is in a tri-state or high impedance condition
when this occurs. Only one driver may be active at a time and the other driver(s) must be tri-stated. The output
modem control signal Request To Send (RTS) is typically used to control the state of the driver. Some
communication software packages refer to RS-485 as RTS enable or RTS block mode transfer.
DIP-switch SW1 is used to control the RS-485 mode functions for the driver circuit. The selections are:
‘RS-422 Mode’ (Always). This is the factory default mode that ensures the transmitter is always enabled. This mode
is intended for Full Duplex applications such as RS-422 or RS-485 4-wire Master mode where tri-state control of the
transmitter is not required.
‘RS-485 Auto Mode’. This mode uses an onboard MicroChip PIC microcontroller to sense the baud rate and control
the transmitter enable signal based on the detected baud rate. The logic assumes a minimum baud rate of 1200bps
and a word length of 10 bits (1 start bit, 8 data bits, and 1 stop bit). For baud rates of 38.4K or less, line turnaround
should not exceed 4 bit times, 57.6K should not exceed 10 bit times, and 115.2K should not exceed 20 bit times after
successfully autobauding.
‘RS-485 RTS Enable Mode’. The ‘RTS’ enable mode uses the ‘RTS’ modem control signal to enable the RS-485
interface and provides backward compatibility with existing software products. Sealevel Systems’ serial driver
should be used and configured for ‘RTS’ control providing a robust RS-485 solution.
‘RS-485 Data Enable Mode’. The ‘Data’ enable mode uses the transmit data stream to enable/disable the transmitter.
When the data bit is High (logic 1), the transmitter will be tri-stated and relies on the line biasing resistors to place
the line in the proper state. For this reason, line termination cannot be used thus reducing the data rate and maximum
cable length. This mode should only be used in applications that prevent the use of the RS-485 Auto Mode or
Sealevel Systems’ serial driver.
Sealevel Systems DIN485+ Page 2
Card Setup
Communication Mode Examples (Dip switch SW1)
ON
OFF
1
2
Figure 1- Dip switch SW1, RS-422
OFF
ON
1
2
Figure 2 – Dip switch SW1, RS-485 ‘Auto’ Enable
ON
OFF
1
2
Figure 3 – Dip switch SW1, RS-485 ‘RTS’ Enable
OFF
ON
1
2
Figure 4 – Dip switch SW1, RS-485 ‘Data’ Enable
Sealevel Systems DIN485+ Page 3
Card Setup
Line Termination and Receiver Echo Off/On
Typically, each end of the RS-485 bus must have a line-terminating resistor (RS-422 terminates at the receive end
only). A 120-ohm resistor is across each RS-422/485 input in addition to a 1K-ohm pull-up/pull-down combination
that biases the receiver inputs. DIP-switch SW2 allows customization of this interface to specific requirements. Each
DIP-switch position corresponds to a specific portion of the interface. If multiple DIN485+ adapters are configured
in an RS-485 network, only the adapters on each end should have DIP-switch SW2 position 1 on. One adapter
should have DIP-switch SW2 positions 2 and 3 on. Refer to the table below for each position’s operation.
DIP-switch SW2 position 6 is used to control the RS-485 enable/disable functions for the receiver circuit and
determines the state of the RS-422/485 driver. The RS-485 ‘Echo’ is the result of connecting the receiver inputs to
the transmitter outputs. Every time a character is transmitted, it is also received. This can be beneficial if the software
can handle echoing (i.e. using received characters to throttle the transmitter) or it can confuse the system if the
software does not. To enable the ‘No Echo’ mode DIP-switch SW2 position 6 should be on.
SW2 Function
1 Adds or removes the 120-ohm termination
2 Adds or removes the 1K-ohm pull-up resistor in the RS-422/RS-485 receiver circuit (Receive data only)
3 Adds or removes the 1K-ohm pull-down resistor in the RS-422/RS-485 receiver circuit (Receive data only)
4 Connects TX+ to RX+ for RS-485 two-wire operation
5 Connects TX- to RX- for RS-485 two-wire operation
6 Receiver Echo Off/On (On = Echo Off)
ON
OFF
1
2
3
4
5
6
Figure 5 – Dip switch SW2, Line Termination and Echo Off/On
Sealevel Systems DIN485+ Page 4
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