Chinese Version

CANmodem/CANopen

-For remote access to CANopen systems via telephone line

CANmodem is an intelligent gateway that allows remote access to CANopen systems via a conventional AT compatible modem. The programming interface for Windows 2000/XP (API) provides functions for transmitting and receiving SDO messages as well as for configuration of the CANmodem. PC-based service and monitoring programs can simply access the CANmodem by means of the API via a telephone dial-up connection.

The CANmodem is a full CANopen node and has an object directory, two server SDOs and 127 client SDOs. Data of any length can be read and written via the client SDOs (segment size via Modem is 231 bytes). The module can act as a heartbeat producer and as a heartbeat consumer, can monitor up to 16 devices and transmit corresponding events in the CANopen network such as NMT events or heartbeat events. In addition, transmission and reception of any layer 2 messages is possible. This function can be used for transmitting and receiving any PDOs or for using the CANmodem with any CAN protocol.

In the event of service, many SDO accesses to the individual devices occur. The API not only allows SDO accesses to be initiated individually, but a whole list of SDO accesses, to be initiated, can be transmitted to the CANmodem. This list is then processed locally by the CANmodem and the result is then returned. With many SDO accesses, the propagation time via the telephone line plays a minor role.

The CANmodem can be connected to a conventional external AT-compatible modem via the full-duplex RS232 interface or directly to the PC. Communication occurs via a serial protocol based on the HDLC standard. For modem adaptation, a configurable init string can be saved in the object directory.

Connection between the PC and the CANmodem is made by means of a safe callback procedure. For this, the caller gives the CANmodem his callback number, which is checked by the CANmodem based on a white list. If the relevant number is entered in the white list, the modem calls the caller back and starts an authorization phase based on the CHAP protocol. After successful authorization, the PC application can run all functions on the CANmodem.

Technical Data

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