Manuals / B&B Electronics / Computer Equipment / Switch

B&B Electronics RS-485 manual Appendix B Analog Input Impedance

Models: RS-485

1 39
Download 39 pages 36.61 Kb
Page 35
Image 35

Appendix B: Analog Input Impedance

When interfacing with an A/D converter, it is important that the device you are connecting can drive the A/D input. To determine if your device can drive an A/D input, there are three factors you must consider:

∙Output impedance of the device

∙Input impedance of A/D

∙A/D sampling time

The goal is to have the voltage at the A/D input settle to a voltage close to the output voltage of the device in a time frame that is less than the A/D sampling time. (Close to means a value significantly less than the resolution of the A/D). If the voltage does not settle fast enough, errors will occur in the reading, resulting in a loss of resolution.

The next section, titled “Simplified Analog Input Analysis,” contains information from Texas Instruments data sheet on the TLC1543. The TLC1543 is the A/D converter that is used on the 485SDA10. This section provides a simplified calculation which can be used to determine the maximum output impedance the device can have to settle the A/D input to a voltage within one half LSB.

For the 485SDA10:

tc = 100us

Using this information:

Rs ≤ 170kΩ

If the output impedance of your device is 170kΩ, you should figure an additional error of ½ LSB.

It should be pointed out that this is a simplified analysis and there other several other factors that must be considered (pin capacitance, noise immunity, etc.). The data sheet for the TLC1543 states that “The driving source impedance should be less than or equal to 1kΩ.” B&B Electronics recommends placing a voltage follower between the 485SDA10 and any device with output source impedance greater than 1kΩ.

485SDA103798 Manual

Appendix B

B-1

B&B Electronics -- 707 Dayton Rd. -- PO Box 1040 -- Ottawa, IL 61350

PH (815) 433-5100 -- FAX (815) 434-7094

Page 34 Page 36
Page 35
Image 35
B&B Electronics RS-485 manual Appendix B Analog Input Impedance
Page 34 Page 36

RS-485 specifications

B&B Electronics is renowned for its reliable and efficient solutions for industrial communication, and their Multi-Interface Ethernet Serial Servers stand out as versatile tools for connecting legacy serial devices to modern Ethernet networks. The compatibility with various serial communication protocols, including RS-485, RS-232, and RS-422, makes these servers indispensable in numerous applications that require reliable data transfer.

One of the main features of B&B Electronics Multi-Interface Serial Servers is their ability to support multiple serial communication standards. This flexibility allows businesses to integrate older equipment with newer technologies seamlessly. The servers can act as a bridge, ensuring that data from RS-232 devices can be transmitted over Ethernet networks without modification.

These servers also boast a robust design that is built for industrial environments. With an operating temperature range suitable for harsh conditions, they ensure uninterrupted service in settings such as factories or outdoor installations. The metal housing of the devices provides durability and protection from physical damage, ensuring long-lasting performance.

In terms of connectivity, B&B Electronics Multi-Interface Serial Servers come with numerous options to accommodate different network configurations. They support various IP addressing schemes, allowing for easy integration into existing network infrastructures. Their Ethernet compatibility means they can handle high-volume data traffic, making them ideal for applications that demand high-speed communication.

Another significant feature is their user-friendly configuration options. The servers can be configured via a web interface, providing an intuitive and straightforward approach for users to set up and manage their devices remotely. This feature is especially beneficial for businesses with distributed operations, as it allows for easy monitoring and management from a central location.

The serial servers also incorporate advanced technologies such as TCP/IP and UDP protocols, enhancing data transmission reliability. This ensures that even in instances of network interruptions, data is not lost, thus maintaining the integrity of information being communicated between devices.

In summary, B&B Electronics Multi-Interface Ethernet Serial Servers serve as a crucial link between legacy serial devices and modern Ethernet networks. Their flexibility, robust design, and user-friendly features make them a preferred solution for industries looking to improve their communications infrastructure and streamline their operations. With the integration of cutting-edge technologies, these servers not only meet the current demands but also adapt to future advancements in network communications.