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Black Box SC121A, SC120A-R2 manual Scsi Installation Tips, Scsi Technical Information

Models: SC121A SC120A-R2

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CHAPTER 6: SCSI Technical Information

6.1.5COMMON PROBLEMS

The majority of problems encountered with SCSI-bus installations are due to unbalanced or improper impedances on the SCSI-bus transmission cables caused by varying manufacturers’ peripheral devices. SCSI terminators compensate for these inherent impedance mismatches on a SCSI bus where peripheral devices such as hard drives, CD-ROM drives, scanners, or printers are used.

6.1.6PASSIVE TERMINATORS

The most basic is a passive-resistance style terminator. This is usually supplied with peripherals and frequently does a poor job of balancing the impedance of the SCSI bus. Passive terminators are resistor networks that allow signal voltages to vary with the load and terminator power supplied, resulting in unstable signals from end to end on the bus and causing data errors. Passive terminators are no longer recommended by ANSI for designs.

6.1.7ACTIVE TERMINATORS

Active terminators add a voltage regulator to the circuit to regulate signal voltages with varying loads and terminator power, allowing a consistent signal to be transmitted everywhere on the bus. This in turn compensates for the varying bus lengths and signal loads. All lines are terminated through 110-ohm resistors, which are applicable to all narrow and wide single-ended applications. Active termination is the minimum ANSI-recommended termination.

6.2 SCSI Installation Tips

•Keep your SCSI chain short. Official SCSI specifications limit the length of a SCSI chain to no more that 6 m (20 ft.) for single-ended or 25 m (82 ft.) for differential. Practical experience says the shorter, the better. The maximum length you should allow between devices is 3 ft. (0.9 m).

•Never assign the same SCSI ID number to two devices residing on the same bus. SCSI uses these numbers as addresses to ensure that information goes to the correct location. Giving two devices the same address can result in lost information.

•Know that some SCSI-ID numbers may be reassigned. Internal boot hard drives are usually set to ID “0” while secondary hard drives are set to “1”. Motherboards or host adapters are generally set to ID “7”.

•Always terminate the first and last devices on the chain. Drives purchased specifically for internal use nearly always arrive with terminators installed. If in doubt, call the vendor you purchased the device from.

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Black Box SC121A, SC120A-R2 manual Scsi Installation Tips, Scsi Technical Information
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SC121A, SC120A-R2 specifications

The Black Box SC120A-R2 and SC121A represent the cutting edge of industrial networking devices designed for robust performance and versatility in various environments. These devices are tailored for applications that require reliable data transmission, making them essential in modern automation and control systems.

One of the standout features of the Black Box SC120A-R2 and SC121A is their advanced serial-to-Ethernet conversion capability. This functionality allows users to connect legacy serial devices to Ethernet networks seamlessly. With support for multiple protocols, including TCP/IP and UDP, these converters ensure smooth communication between devices, regardless of their original architecture.

Both models are engineered to withstand harsh industrial conditions. They feature a rugged construction that includes high-quality enclosures designed for durability and protection against dust, moisture, and extreme temperatures. This resilience makes them ideal for use in factories, transportation, and other challenging environments.

In terms of connectivity, the SC120A-R2 and SC121A come equipped with multiple serial ports, enabling simultaneous connections to various devices. The auto-sensing capability of these ports simplifies installation and configuration, making them user-friendly for both technical and non-technical personnel. Users can easily manage and monitor connections through a straightforward web-based interface.

Additionally, these devices incorporate advanced security features, including encryption and authentication protocols, ensuring that data transmission remains secure from potential threats. This focus on security is crucial for industries where sensitive data is transmitted, enhancing overall system integrity.

The SC120A-R2 and SC121A also support a range of network configurations, allowing for flexibility in deployment. Their compatibility with various operating systems ensures that users can integrate them into existing systems without significant modifications.

Moreover, these models offer flexibility in power options, supporting both PoE (Power over Ethernet) and traditional power supply methods. This versatility enables easy installation without the need for additional power infrastructure.

Overall, the Black Box SC120A-R2 and SC121A are sophisticated networking devices that combine advanced technology with rugged design. Their ability to bridge the gap between legacy serial interfaces and modern Ethernet networks, coupled with robust features and security measures, makes them a valuable asset for numerous industrial applications. Whether in a manufacturing plant or a transportation hub, these devices provide reliable, efficient, and secure communication solutions that meet the demands of today's connected world.