SHORT HAUL MODEM (SHM-FSK)

4. Operation

Point-to-point, full- or half-duplex operation is usually conducted with the both the Master and Remote SHM-FSK carriers on all the time. This is achieved by placing the P4 jumper in the B-C position and either not connecting the RTS line (DB25 pin 4) to the SHM-FSKs or making sure that the RTS line supplied by the devices connected to the SHM-FSK is either floating or logic high.

In half duplex, multi-drop operating mode, with the P4 jumper in the A-B position, the RTS line of the intelligent device that a Remote SHM-FSK is connected to (PC, PLC, or RTU) is used to control the the SHM-FSK’s transmitted carrier. When logic is low, the carrier is turned off; when logic is high, the carrier is turned on. If the RS-232 cable is disconnected, the RTS connection on the SHM-FSK is biased low and the carrier remains off. (If the P4 jumper is in the B-C position, the RTS connection is biased high and the carrier will stay on.)

When properly configured, the SHM-FSK is capable of half- or full-duplex data transmission at rates up to 9600 baud. The SHM-FSKs require no settings for data rate and will operate transparently as data is fed to them. They will begin communicating data as soon as connections are made and they are powered up.

15

Page 13 Page 15
Page 14
Image 14
Black Box MD3318, RS-485, MD3317, ME840A-M, ME840A-S manual Operation
Page 13 Page 15

ME840A-M, ME840A-S, MD3318, MD3317, RS-485 specifications

The Black Box IC113C and IC175C are part of a series of versatile RS-485 interface converters designed to facilitate reliable data transmission over long distances. RS-485 is a standard defining the electrical characteristics of drivers and receivers for use in serial communications systems, and these specific Black Box converters exemplify the technology's adaptability and robustness.

The IC113C is an RS-485 to RS-232 converter, providing a seamless transition between these two common serial communication protocols. With a compact design, it boasts an operating temperature range of -40 to 85 degrees Celsius, making it suitable for harsh environmental conditions. Its key feature includes the ability to extend the communication distance up to 4,000 feet, which is ideal for industrial applications where devices may be far apart. Additionally, the IC113C includes built-in surge protection, ensuring that the device can withstand electrical noise and spikes, ultimately increasing the system's reliability.

On the other hand, the Black Box IC175C serves as an RS-485 to USB converter, bridging older serial devices with modern USB interfaces. This converter is critical for users wanting to connect legacy equipment to contemporary computing systems. Featuring a plug-and-play design, the IC175C is easy to install with no external power supply required, as it is powered directly through the USB connection. It also supports data rates up to 115.2 Kbps, ensuring fast and efficient data transfer.

Both models employ differential signaling, which enhances noise immunity and allows for greater transmission distances compared to single-ended communication standards. Furthermore, the converters support multiple nodes on the same bus, accommodating a network of devices without requiring complex wiring schemes.

In summary, the Black Box IC113C and IC175C offer essential features that cater to diverse industrial and commercial applications. With their robust construction, extensive operating ranges, and compatibility with various communication protocols, these converters enhance system interoperability and provide durable solutions for long-distance data communication needs. Whether connecting legacy systems or extending communication capabilities, these devices exemplify reliability and efficiency in modern data transmission technologies.
Top Page Image Contents