Module puts synchronous comms on USB port

Isatec has completed the design and testing of its new USB HDLC module, and the first units are planned to be installed during April.

Isatec has completed the design and testing of its new USB HDLC module, and the first units are planned to be installed during April.

The module consists of a half-Eurocard-sized card enclosed within a robust aluminium case which is powered either from the USB port or an external adapter (9-24V DC).

The module uses HDLC (High Level Data Link Control), which is a synchronous serial protocol, and is not compatible with the asynchronous communication that is used by a standard PC serial port.

The USB HDLC module converts the synchronous HDLC protocol to an asynchronous protocol accessed over a standard USB serial port.

Drivers are available for various operating systems.

The USB HDLC module supports UNC unbalanced operation, normal response mode, half-duplex and multidrop, two-, four- or six-wire RS485 HDLC connections can also be made.

HDLC transmit and receive frequencies are fixed at 64Kbit/s and NRZI modulation coding is used.

It also handles multiple frames, frame windowing, frame check pointing, timeouts and retries.

The USB HDLC module acts as a primary (host) station with multiple secondary stations.

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