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Tait T2000-A76, Operation Manual

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30

M2303-00-P00-805

March 2003

SEND_SDM

 (PC to despatcher radio)

The SEND_SDM command requests the modem to send a Short Data Message (SDM). The PC sends the SDM 
directly to the A76, and the T201X immediately keys up the transmitter. After the specified SDM Lead In Delay 
the modem sends the SDM.

It has the format :

[LEAD_IN_DELAY] [DATA_MESSAGE_ID] [COMMAND] [DATA]

[PARAMETER]

Function

[LEAD_IN_DELAY]

SDM Lead In Delay

. Two ASCII hex characters representing the SDM Lead In 

Delay between radio transmitter key-up and the start of data transmission. The 
range that can be entered is 00 to FF. 
The Lead In Delay is calculated by multiplying the number by 20 ms. 
A minimum of at least 100 ms of Lead In Delay is required, so 00 to 04 will 
always be treated as 05. This corresponds to a Lead In Delay between 100 ms 
and 5.1 seconds, in steps of 20 ms. Refer to the 

Polling the Remote AVL radio

 

section.

[DATA_MESSAGE_ID]

SDM Data ID

. An 8-character string representing the SDM Data ID of the 

radio to which the SDM is sent. It can be any alphanumeric characters. “ 

*

 “ is 

the wildcard for any character. e.g. 12

**

5678

When a radio receives a SDM message, the Data ID is checked against the ID 
entered in the radio database (using the 

PROGRAM

 command). If the Data ID 

matches, the received SDM data is stored and the radio sends a PROGRESS 
command to indicate this. 
If the Data ID does not match then the SDM data is ignored.

[MESSAGE]

SDM text

. Maximum 32 characters of SDM data. [MESSAGE] is optional.

Summary of Contents for T2000-A76

Page 1: ...T2000 A76 AVL Modem Operation Manual Tait Electronics Limited Corporate HQ PO Box 1645 Christchurch New Zealand Tel 64 3 358 3399 Fax 64 3 358 0340 Web www taitworld com March 2003 M2303 00 P00 805 ...

Page 2: ......

Page 3: ...n Title Page 1 Overview 5 1 Operation 6 2 Compatibility 8 3 GPS Interfaces 9 4 Programming the A76 12 5 Operation Sequences 14 6 Commands to the Remote Radio 17 7 Responses from the Remote Radio 21 8 CCDI Reference 24 ...

Page 4: ......

Page 5: ... the Tait CCDI Computer Controlled Data Interface over air command protocol to communicate with the remote radio CCDI commands containing short data massages SDMs are sent to the remote radio by the PC AVL application Each SDM contains a command which tells the remote radio to one of the following send an AVL report send database information set the Group Delay Time control the AUX line output res...

Page 6: ... or an emergency activation occurs an AVL report with the stored data is immediately sent to the despatcher radio and saved by the AVL application Refer to the section NMEA 0183 RMC Sentence Format for a description of the NMEA RCM format All RMC fields are initialised with 0 Radio Signalling The signalling between the despatcher radio and the remote AVL radio uses the Tait CCDI V2 0 terminal and ...

Page 7: ... to section 8 Responses from the Remote Radio for the response message format details A76 Configuration Programming using NMEA The serial RS232 serial port on the A76 modem is configured to expect NMEA type format This means that the programming of the A76 database must be done using NMEA sentences rather than sending a standard CCDI Program command as is used with both the T2000 A75 Modem and the...

Page 8: ... fitted set the default Lead In Delay in the A76 configuration to 200 ms or greater The Lead In Delay can be reprogrammed as low as 40 ms but the Economy mode must be disabled Despatcher Radio PGM Settings The despatcher radio may be a Tait Orca a Tait Radio Modem or a T2000 with a A75 fitted Regardless of which radio is used the modem must have Auto Acknowledge set to disabled GPS Receiver The GP...

Page 9: ...RS232 D Range socket at the rear of the T201X radio has the following configuration not available in the standard T201X without a T2000 A76 PCB fitted Caution Note that RS232 pin labelling can be misleading A straight trough cable is used to connect the GPS receiver to the T201x radio Note The start and stop bits are removed by the modem for the over air transmission of data The FFSK data sent is ...

Page 10: ...three letter sentence ID followed by data fields separated by commas The sentence is terminated with a checksum and a carriage return and line feed A sentence can contain up to 82 characters If a data field is empty a comma is still inserted This application of the NMEA standard uses the RMC sentence format which is especially formulated for AVL data The RMC sentance structure structure is RMC hhm...

Page 11: ...e dec imal point Not sent in the AVL report ddmmyy date dd day two fixed digits mm month two fixed digits yy year two fixed digits Only dd day sent in AVL report 020 3 magnetic variation 20 3 degrees magnetic variation Not sent in the AVL report E magnetic variation reference E east subtracts from the True course W west adds to the True course Not sent in the AVL report hh checksum is a delimiter ...

Page 12: ...urational information Bit 1 and Bit 0 Baud Rate default 10 Selects the baud rate of the A76 serial port 00 1200 bps 01 2400 bps 10 4800 bps 11 9600 bps Bit 2 PTT ANI Report default 0 If enabled an ANI report is sent whenever the PTT is pressed Refer to PTT Activated AVL Reporting 0 No ANI report 1 ANI report Sent Bit 3 Over Air Baud Rate default 0 0 1200 bps 1 2400 bps Note the Tait Orca does not ...

Page 13: ...or any character e g 12 5678 ITEM6 Emergency AVL Report Count default 03h Two ASCII hex characters to set the number of AVL reports sent once Emergency mode has been activated Range 00 to FFh 255 if 00 then the Emergency AVL reports are sent indefinitely ITEM7 Emergency AVL Report Period default 05h 5 seconds Two ASCII hex characters to set the interval between consecutive AVL reports once Emergen...

Page 14: ...e radios can be done more efficiently by using a Group Poll A Group Poll is sent by inserting a wildcard into the DATA_MESSAGE_ID part of the SEND_SDM command The DATA_MESSAGE_ID is an 8 character string representing the SDM Data ID of the radio to which the SDM is sent It can contain any alphanumeric characters and can be inserted as the wildcard for any character e g 12 5678 When a radio receive...

Page 15: ...iary output from the A76 uses the RS232 CTS line on the A76 serial port to switch external devices on or off It can be remotely controlled by the despatcher radio by sending a AUX ON or AUX OFF message This feature can be enabled or disabled by the A76 configuration ...

Page 16: ...an emergency switch activation Emergency AVL report period the idle time between AVL reports sent after an emergency switch activa tion The despatcher address the address that the AVL report is sent to The Emergency mode feature can be enabled or disabled by the A76 configuration PTT Activated AVL Reporting The A76 can be configured to send an unsolicited AVL report each time the PTT is pressed or...

Page 17: ...y 20 ms A minimum of at least 100 ms of Lead In Delay is required so 00 to 04 will always be treated as 05 This corresponds to a Lead In Delay between 100 ms and 5 1 seconds in steps of 20 ms Refer to the Polling the Remote AVL radio section DATA_MESSAGE_ID The DATA_MESSAGE_ID is an 8 character string representing the SDM Data ID of the radio to which the SDM is sent It can be any alphanumeric cha...

Page 18: ...nt to the default despatcher address 1 the AVL report is sent to the return address specified Bit 4 6 Command Type 000 Poll poll for a AVL report from the remote radio 001 Read Database read a database item from the remote radio 010 Program Database program database item into the remote radio 011 Control AUX used for controlling the AUX to the remote radio 100 110 reserved 111 Reset used for reset...

Page 19: ... 30 30h 19h 0001 1001 followed by the address where 30h is ASCII for 0 and 38h is ASCII for 8 Read the Group Delay Time and send ACK 91h plus the result to the return address 00000800 Program Database 010 001 program the Group Delay Time 010 111 the command will be ignored If a return address is sent it is sent in the DATA bytes as is the Group Delay Time data The address precedes the Group Delay ...

Page 20: ... command will be ignored If a return address is sent it is sent in the DATA byte A Control AUX ACK is sent back Examples COMMAND 30h 0011 0000 Sets the AUX CTS signal at the remote radio to ON and sends a Control AUX ON ACK B0h to the default despatcher address COMMAND 39 30 30 30 30 30 38 30 30h 39h 0011 1001 followed by the address where 30h is ASCII for 0 and 38h is ASCII for 8 Sets the AUX CTS...

Page 21: ... a one byte responses to the command from the AVL application The table below shows the structure of the RESPONSE RESPONSE Bit Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Function 1 Response Type Radio Status ACK Parameter RESPONSE parts Function Byte 1 Bits 0 3 Radio Status ACK Parameters These bits are set depending on the Response Type being sent Refer to the table below for the options Byt...

Page 22: ...of the AVL Report Read Database ACK 001 0000 sends the software version 0001 sends the Group Delay Time The returned data comes immediately after the ACK Parameters Examples If a Read Database command is sent to read the software version the response is RESPONSE 90 32 33 30 33 41 35 32 30h 90h 1001 0000 followed by the software version 2303A520 as 8 bytes of ASCII If a Read Database command is sen...

Page 23: ...D 4 Byte 4 1 HH HH Hour two digit BCD number Byte 5 1 MM MM Minute two digit BCD number Byte 6 1 SS SS Second two digit BCD number Byte 7 1 F Ld F Latitude Ref bit 4 0 N 1 S bit 5 0 E 1 W Ld Latitude degrees two digit BCD number Byte 8 Ld 1 Lm Ld Latitude degrees cont Lm Latitude minutes two digit BCD number Byte 9 Lm Ls Lm Latitude minutes cont Ls Latitude decimal points two digit BCD number Byte...

Page 24: ...ERS field is 42 characters The maximum length of the command packet is therefore 47 SIZE 2F characters Calculating the CCDI CHECKSUM Note This is not required if an AVL PC application such as is used to send commands CHECKSUM is calculated by applying the following algorithm 1 Take the modulo 2 sum of all message bytes preceding CHECKSUM 2 Retain bits 0 to 7 discarding any higher order bits result...

Page 25: ... 44 30 35 30 38 30 30 54 45 53 54 48 69 21 426h 2 Retain bits 0 to 7 discarding any higher order bits resulting from the summation 26h 3 Form the two s complement of the remainder 26h 0010 0110 two s complement 1101 1010 4 Convert the binary number into two ASCII hex digits MSD first 1101 1010 DA The following CCDI commands are sent between the PC AVL application and the despatcher radio ...

Page 26: ...message is s05Hello34 PARAMETER Function SDM_DATA This can be a maximum of 32 characters If there is any buffered SDM data in the EEPROM the SDM data is sent to the PC If there is no data available then the command is sent with no PARAMETERS field Message Field Parameter A76 Response IDENT GET_SDM s SIZE Size of parameter field 05 PARAMETERS SDM_DATA the SDM text message from the A76 EEPROM Hello ...

Page 27: ...iver no longer detects an RF signal on the current channel This message is sent when the current chan nel becomes available PTYPE 07 PTT Mic Activated This message indicates that the PTT has been pressed This message is sent whenever the PTT is pressed in an attempt to transmit PTYPE 08 PTT Mic Deactivated This message indicates that the PTT has been released This message is sent whenever the PTT ...

Page 28: ...gress message is p0207C7 Message Field Parameter A76 Response IDENT PROGRESS p SIZE Size of parameter field 02 PARAMETERS PTYPE 07 the PTT mic has been activated by the FUNCTION command 07 CHECKSUM The checksum for the message string calculated by the modem C7 ...

Page 29: ...TYPE 0 Query Model message The T201X radio and CCDI information is returned to the PC as a MODEL message QUERY_TYPE 1 Query SDM message The SDM message is returned to the PC as a GET_SDM message QUERY_TYPE 2 Query Database message QUERY_TYPE 3 Query S W Version message QUERY_TYPE Blank Same as QUERY_TYPE 0 Message Field Parameter Entered at terminal IDENT QUERY q SIZE Size of parameter field 01 PA...

Page 30: ... number by 20 ms A minimum of at least 100 ms of Lead In Delay is required so 00 to 04 will always be treated as 05 This corresponds to a Lead In Delay between 100 ms and 5 1 seconds in steps of 20 ms Refer to the Polling the Remote AVL radio section DATA_MESSAGE_ID SDM Data ID An 8 character string representing the SDM Data ID of the radio to which the SDM is sent It can be any alphanumeric chara...

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