Wireless Link Corporation CVDM-2000 CVDM-2000 User’s Manual This document describes the interface specifications for using CVDM-2000 in a product application. Warning: While this device is in operation, a separation distance of at least 50 centimeters (20 inches) should be maintained between the radiating antennas and the body of the user or nearby persons. Caution: Changes or modifications net expressly approved by Wireless Link Corporation could void the user’s authority te operate this equipment.
CVDM-2000 User’s Manual Warning: While this device is in operation, a separation distance of at least 50 centimeters (20 inches) should be maintained between radiating antenna and the body of the user or nearby persons. This manual describes the interface specifications for using CVDM-2000 in a product.
RECESS LINK rp ar ati J mm \l/ WIRELESS LINK SOFTWARE INTERFACE SPECIFICATION CVYDM2000 MODULE “C” VERSION Doc. Revision: 1.1 Doc. Date: 2/17/98 CVDM2000 REV C.
Revision History 16/21/97 Rev LO J. Olson Derived from WAP “B” specification, Differences are: All references to CDC changed to “CVDM2000 Module”. PDI was expanded to include much of the original WAP, as a result WAP is now a special mode of operation for the Hayes Modem option documented in “Wireless Link Packet Data Interface Supplement, CV Hayes Modem Option”. The PDI protocol and standard messages are documented m “Wireless Link Packet Data Interface, CV All Versions”.
TABLE OF CONTENTS 1.0 HARDWARE INTERFACE TO CVDM2606 MODULE 2.0 SOFTWARE INTERFACE TO CVDM2000 MODULE 2.1 INTERFACE DATA FORMAT WAP 2.2 SUMMARY OF WAP MESSAGES 2.2.1 Messages sent ta CVDM2000 Module from data center 2.2.2 Messages sent to data center from CVDM2000 Module 3.0 MESSAGE DESCRIPTIONS 3.1 Message: Idle frame (01) 3.2 Message. Unrecognized message type (62, ony. 3.3 Message. Alarm event (40) ER Message: Report Long Navigation Message (41, 06) 2: Set or Report Position/Velocity Solution (41, 07).
1.0 HARDWARE INTERFACE TO CYDM2000 Module The CVDM2000 Module firmware designed by Wireless Link supports a built-in Hayes compatible modem to allow control and monitoring via the AMPS cellular network. This Modem supports the standard CIT V.22 bis (2400 bps), Bell 212A and V.22 (1200 bps), and Bell 103 (300 bps) data modes. Calls by the CVDM2000 Module originate and answer at the following settings: Data Mode: Bell 212A (1200 bps) Baud Rate: 1200 Parity: None Stop Bits: 1 2.
2.1 INTERFACE DATA FORMAT WAP The following describes the Wireless Link Air Protocol (WAP) which is based on Wireless Link Corporation’s Alphabetized Data Interface (PD. This alphabetized interface was designed to use a minimum of code and data resources to handle the encoding and decoding, yet provide rugged error detection and reliable data transport. / r 1 The following shows the format of each data packet that gets sent to and from the CVDM2000 Module.
2. Generate a new ACK SEQ number to send out as acknowledgment of’ receiving a valid frame. The ACK SEQ field is a two-bit sequence number equal to the SEND SEQ number of the most recent, valid received frame. The ACK SEQ number is used to acknowledge successful reception of a frame, When a connection is first established between the CYDM2000 Module and the data center, the sequence numbers are both reset to zero.
unsigned short char b, unsigned short crc) { unsigned short s; s = {unsigned short)b * (ere & 0xff); s§=§ NM return (5); } The CRC for a message can then be calculated for a message as follows: ere = 0); / initial cre calculation for (index = 1; index < lengthen; index++) { } ere = cred; A faster run-time implementation is to generate a CRC look-up table as follows: unsigned short for {index = 0; index < 0x100; index++) { } ere_tablefindex]| = 0); Then use the following routine instead of critter( ): unsign
Packet Decoding: If STF is received, do not include as part of SEQ, DATA or CRC. The next byte received, regardless of its value, becomes the actual SEQ, DATA or CRC. Both bytes are included in the checksum calculation. If EOP is receive without a preceding STF, then this is the end of the packet. CVDM2000 REV C.