Omega Engineering RS-422/485 manual Line Termination, Name Function

Page 13

Card Setup

Line Termination

Typically, each end of the RS-485 bus must have line terminating resistors (RS-422 terminates at the receive end only). A 120-ohm resistor is across each RS-530/422/485 input in addition to a 1K ohm pull-up/pull-down combination that bias the receiver inputs. Headers J1E through J4E allow the user to customize this interface to their specific requirements. Each jumper position corresponds to a specific portion of the interface. If multiple OMG-ULTRA-COMM422adapters are configured in an RS-485 network, only the boards on each end should have jumpers T, P & P ON. Refer to the following table for each position’s operation:

Name

Function

PAdds or removes the 1K ohm pull-down resistor in the RS-422/RS-485 receiver circuit (Receive data only).

PAdds or removes the 1K ohm pull-up resistor in the RS-422/RS- 485 receiver circuit (Receive data only).

T

Adds or removes the 120 ohm termination.

LConnects the TX- to RX- for RS-485 two wire operation.

L Connects the TX+ to RX+ for RS-485 two wire operation.

P

P

T

L

L

Figure 11 - Headers J1E - J4E, Line Termination

OMG-ULTRA-COMM422

Page 9

Page 12 Page 14
Image 13
Page 12 Page 14
Contents User’sGuide Mexico CanadaBenelux Czech RepublicContents Figures Introduction Factory Default SettingsOverview What’s IncludedSwitch Port Card SetupAddress Selection Port # Connector Location Address Example Base=2E0 Switch Settings Address lines à Address SelectedIRQ Selection Jumper SelectionsInterrupt Modes J1ARS-485 Enable Modes Headers J1D- J4D, RS-422 Interface Mode Examples J1D J4DHeaders J1D- J4D, RS-485 ‘RTS’ Enabled, with ‘No Echo’ Name Function Line TerminationDIV4 DIV2 Clock ModesFor this Data Rate Choose this Data Rate Baud Rates and Divisors for the ‘Div1’ modeFor this Data Rate Choose this Divisor Baud Rates and Divisors for the ‘Div2’ mode Operating System Installation For Windows Users InstallationOther Operating Systems Modem Control Signal Considerations FeaturesTechnical Description Interrupts Why use an ISP? DB-37 Connector Pin Assignments Connector Pin Assignments DB-9 Pin AssignmentsSignal Name Pin # Mode Port #Specifications Appendix a Troubleshooting OMG-ULTRA-COMM422 Appendix B How To Get Assistance RS-422 Appendix C Electrical InterfaceRS-485 Appendix D Asynchronous Communications Asynchronous Communications Bit DiagramAppendix E Silk-Screen Appendix F Compliance Notices WARRANTY/DISCLAIMER Temperature

RS-422/485 specifications

Omega Engineering is a renowned leader in the field of measurement and control technologies, particularly in the realm of data communication for industrial automation. The RS-422 and RS-485 protocols are part of Omega's robust offering, designed to facilitate reliable and efficient data transmission over relatively long distances. These protocols are widely used in various applications ranging from industrial machinery to building automation systems.

One of the main features of RS-422 is its ability to support long-distance communication, allowing data to be transmitted up to 4,000 feet (approximately 1,200 meters) at speeds of up to 10 Mbps. This is achieved through the use of differential signaling, which provides improved noise immunity compared to single-ended signaling systems. RS-422 employs a single transmitter and multiple receivers, making it ideal for point-to-multipoint configurations.

On the other hand, RS-485 extends the capabilities of RS-422 by allowing multiple devices to be connected on the same bus. It supports up to 32 devices, which can be either transmitters or receivers, making it exceptionally versatile for networking applications. RS-485 can communicate effectively over distances up to 4,000 feet and at speeds of 10 Mbps as well. This makes it an attractive option for applications where several devices need to communicate with a central controller.

An essential characteristic of both protocols is their resilience to electromagnetic interference, which is often a concern in industrial environments. The differential signaling used in RS-422 and RS-485 reduces noise susceptibility, ensuring data integrity even in challenging conditions. Additionally, these protocols function effectively in half-duplex or full-duplex modes, providing flexibility based on application requirements.

Moreover, Omega Engineering’s implementations of RS-422 and RS-485 comply with established standards, ensuring compatibility with a wide range of devices. This interoperability is crucial for seamless integration into existing systems and enhancing overall productivity.

In summary, Omega Engineering's RS-422 and RS-485 technologies offer robust, reliable, and versatile solutions for data communication in industrial settings. With features such as long-distance communication, multiple device connections, and exceptional noise immunity, these protocols continue to serve as foundational technologies in various automation and control applications. As industries evolve, Omega Engineering remains committed to advancing these technologies to meet the growing demands of modern data communication.
Top Page Image Contents