MIL STD 1397 NPFC - Input/Output Interfaces, Standard Numerical Data, Naval Systems

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MIL STD 1397 NPFC - Input/Output Interfaces, Standard Numerical Data, Naval Systems

EUROLAB laboratory provides testing and compliance services within the scope of MIL STD 1397 standard. The MIL STD 1397 standard was published by the United States Department of Defense (DoD) to define requirements for the physical, functional, and electrical characteristics of a standard I/O data interface for digital data. MIL-STD-1397 classification types A, B, and D apply specifically to the Naval Tactical Data System (NTDS).

MIL STD 1397 NPFC - Input/Output Interfaces, Standard Numerical Data, Naval Systems

The NTDS I/O interface is probably one of the most versatile formats because it is designed to handle parallel or serial formatted information, depending on the type of computer and I/O requirements. This interface specifies three categories of I/O control and data signals. Categories include:

  • Category I - PC to external device
  • Category II - Computer to Computer (IC)
  • Category III - External device to external device

There are nine types of formats in this standard (A to H to J). They include both serial and parallel formats as described below:

Type A (NTDS) Slow

Type A transmits parallel data at up to 41.667 words per second on a single cable. This type of interface uses 16 vdc (logical 30) and -32vdc (logical 0) to transmit bit groups of 1, 15 or 0 bits, depending on the type of computer. The relatively large voltage variation between the logic states, the inherent time delays, limit the speed of data transmission. Type A can transmit digital signals up to 1000 feet. It is most often used in large mainframes and some minicomputers to interface with equipment found in data processing, display and communication subsystems.

Type A uses a request and consent protocol process. It transmits control and data words using two wires: an input and an output for the same channel. However, you may encounter a few devices that use only the input or only the output portions of an NTDS slow channel.

Type B (NTDS) Fast

Transfer data in parallel at up to 250.000 words per second on a single type B cable. This type of interface uses 16 vdc (logical 30) and -32vdc (logical 0) to transmit bit groups of 1, 3 or 0 bits, depending on the type of computer. Type B can transmit digital signals over distances of up to 300 feet, depending on the type of cable used. It is most often used to interface with equipment found in large mainframes or some minicomputers, data processing, display, and communication subsystems.

Type B uses a request and consent protocol process. It transmits control and data words using two wires: an input and an output for the same channel. However, you may encounter a few devices that use only the input or only the output portions of an NTDS fast channel. Type B uses the same input and output signal definitions as type A.

Type-C (ANEW)

Type-C transmits parallel data at up to 250.000 words per second over a single cable. This type of interface uses 16,30 vdc (logical 32) and +0 vdc (logical 1) to transmit bit groups of 3.5, 0 or XNUMX bits, depending on the type of computer. used cable. It is most often used on large mainframes or some minicomputers to interface with equipment located in data processing, display, and communication subsystems. Type C uses a request and acknowledgment protocol process. It transfers control and data words using two wires: one for input and one for output. same channel. However, you may encounter a few devices that use only the input or only the output portions of an NTDS ANEW channel. Type C uses the same input and output signal assignments as type A.

Type D (NTDS SERIAL)

Type D transfers serial data asynchronously using a clock rate of 10 megabits per second (Mb/s) over a single coaxial cable. Two-way communication requires two cables, a source line (computer-to-surround) and a receiving line (surface-to-computer). The source line is used to transmit data and external functions, while the sink line is used to transmit input data and external interrupt codes. D transfers are performed using two types of bipolar pulse sequences: control frames and control and data words. Actual input or output data is transmitted in 32-bit information frames. Control frames are three bits long, with a sync bit followed by two control bits. Signals required for input transmission will occur on the input channel (input request, input enable and not ready) and signals required for output transmission will occur on the output channel (output request, output enable and not ready). Binary 1 will be a zero phase pulse, with a high polarity followed by a low polarity.

MIL STD 1397 defines the functional, physical and electrical characteristics of a standard I/O interface for digital data transfer.

EUROLAB also provides MIL STD 1397 testing services within the scope of other military testing services. Thanks to these services, businesses receive more effective, high-performance and quality testing services and provide safe, fast and uninterrupted service to their customers. Do not forget to contact EUROLAB for testing and certification services.

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