1、 1 General This standard defines the status monitoring and diagnostics protocol (SMDP) used with a general-purpose communication link that connects to equipment used in the production, post-production, and/or transmission of visual and audio information. The communication link is separate and distin
2、ct from the supervisory interface for digital control (ANSI/SMPTE 207M). SMDP may be used when querying equipment for status and diagnostics information. The primary intent of this standard is to establish the protocol between a supervisory controller and associated video/audio equipment. In additio
3、n, it seeks to establish a common set of commands that should be used in SMDP-based systems. A provision allows for manufacturer-specific commands in addition to the common set. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisi
4、ons of this standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. SMPTE RP 165-1
5、994, Error Detection Checkwords and Status Flags for Use in Bit-Serial Digital Interfaces for Television 3 Definitions 3.1 encapsulated SMDP: The lowest layer of the SMDP may be encapsulated as data into other protocols. Using this method, SMDP packets may be transported in open, standard protocols
6、such as TCP/IP. 3.2 message set: From the standpoint of a sender, an issued command/data message sent to a destination and the associated response/data message from the destination. All message transactions between a supervisor and a virtual machine require a message set. 3.3 supervisor: Each system
7、 needs at least one supervisory controller. This controller connects to any and all video/audio equipment that is to be monitored. 3.4 virtual circuit: A transparent, unidirectional, logical communications connection between a supervisor and a virtual machine. The communication path may pass through
8、 other levels of protocol before the circuit is established. 3.5 virtual machine (VM): A logical device consisting of a single device or combination of devices that respond in essence as a generic type of equipment; e.g., VTR, video switcher, router, telecine, etc. The VM is the device under scrutin
9、y when connected to a link that uses the SMDP. Page 1 of 23 pages SMPTE 273M-2003 Revision of ANSI/SMPTE 273M-1995 Copyright 2003 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., White Plains, NY 10607 (914) 761-1100 Approved October 20, 2003 SMPTE STANDARD for Televi
10、sion Status Monitoring and Diagnostics Protocol SMPTE 273M-2003 Page 2 of 23 pages Figure 1 Typical system 4 System elements Figure 1 shows a typical system with links between a supervisory controller and several VM devices. Each device is connected to the supervisor using dedicated communication li
11、nks (TIA-232). Small systems may use directly connected communication links as shown in figure 1. Medium and larger systems may use encapsulated SMDP to provide addressibility, guaranteed delivery, and access to public networks. Encapsulated SMDP leverages the advantage of open, public network stand
12、ards. Although SMDP may be used as shown in figure 1, its main application is as described in annex A. Annex A of this standard gives an example of encapsulated SMDP and how it may be used in a networked environment. As will be shown, SMDP traffic uses only a few ASCII control codes and, as such, ma
13、y be carried by MODEMS without problems. The SMDP supports multidrop addressing. A discussion of multidrop modes is presented in annex B. In general, the supervisor queries the VM using a command from the standard set or one provided by the manufacturer. The VM executes the command and always return
14、s a response when finished. The VM may initiate a call to the supervisor by sending a special command for this purpose. So, the VM may be polled by the supervisor for information or it may send an interrupt to the supervisor indicating that it has information of interest. Most VMs also have a separa
15、te digital control interface input to remotely control the VM. It is the responsibility of the manufacturer to assign priorities to the two interfaces so that both are served but in a time and manner that is best suited for any particular VM. SMDP traffic is processed by software routines (the SMDP
16、processor) in each VM and the supervisor. The SMDP processor may be run as a task under the auspices of the VMs or supervisors operating system. The processor is not multitasking and as such can only process one command at a time. The only exception is the *RST (reset) command which is executed upon
17、 arrival by the SMDP processor (see 6.1 for more information on *RST). 5 Common command and response structure The SMDP defines 11 common commands and response messages that all protocol compliant virtual machines should implement. In addition, there are five that are optional. These are general in
18、nature and not device-specific in any way. In addition, manufacturers may add private commands as long as they follow the byte and packet level protocols defined in this standard. SMPTE 273M-2003 Page 3 of 23 pages Next, the common set is defined and explained. All these message names include an * a
19、s part of the name to identify it as a common command. Manufacturer supplied commands should omit the *. Also, any command that is a query for information must include a ? to identify the query operation. Every command that is issued to a VM causes it to send one of three possible responses back to
20、the supervisor. The possible responses are (1) *ATN:OPC, (2) ATN:CMDERR, or (3) *ATN:QRESP (plus response data structure). The ATN prefix signifies that the VM desires the attention of the supervisor. The OPC response indicates that the OPeration is Complete (no errors either) and the VM may receive
21、 another command. The CMDERR response indicates that the last command issued to the VM was errored in some way. The QRESP response indicates that data corresponding to a Query RESPonse is being sent. The command and response names are case insensitive. Whenever ASCII string data are returned to the
22、supervisor, any given line should not be longer than 62 characters including the carriage return/line feed combination, CRLF. The CRLF set allows for the convenient printing of returned response data. All string lines, regardless of length, should end with an ASCII CRLF combination (HEX 0D 0A). As m
23、any lines as needed may be returned for a query response. Commands, responses, and data are sent between devices using packets. In general, packets to and from a VM are composed as follows. The braces below are used to delimit optional parameters and are not part of the actual command format. Simpli
24、fied packet for an issued command with data: command_keyword:command_keyword. ? parameter,parameter. ; data field Simplified packet for an issued response with data: response_keyword:response_keyword. parameter,parameter. ; data field Commands, responses, and optional parameters go into the command/
25、response field. A command is one or more colon-separated command_keywords. Likewise for a response. Associated data structures, if any, go into the data field. Values within braces are optional. Generally, commands go from the supervisor to the VM and responses go from the VM to the supervisor, but
26、there are exceptions. The keywords and parameters must be printable strings. The following should be observed: 1) Keywords may be concatenated if desired. This is a hierarchical method of command/response naming. Keywords must be separated by colons (:). No colon is needed after the last keyword. 2)
27、 Any optional parameters must be comma (,) separated. There is no trailing comma after the last parameter. There must be a space between the last keyword and any parameters to follow. 3) The command/response field is always terminated with a semicolon (;). No other embedded semicolons are allowed in
28、 the command/response field. A ? is appended to the compound command name if the command is a query. The command/data and response/data form a message set. For every command/data message sent to a receiver, a response/data message is returned. The response is, in effect, a termination for the transa
29、ction. Table 1 summarizes the message names used in SMDP. The classification is as follows: C indicates that the name is a command message to the VM. R indicates that the name is a response message from the VM. CSUP indicates the name is a command message to the supervisor from the VM. If a $ appear
30、s next to the indicator, then command implementation is optional. SMPTE 273M-2003 Page 4 of 23 pages 6 Command messages to the VM 6.1 Command name: *RST (reset) Description: Reset the SMDP processor in the VM upon receipt of this command. This causes a termination of any pending or existing VM SMDP
31、operations and it returns to the idle state. All error and message queues are flushed. Any current packet transmissions to the supervisor are cancelled. However, the *ATN:OPC is sent in response. When the VM powers on, the SMDP processor should be reset to the idle state. If the VM is attached to a
32、multidrop link, or equivalent, this command causes the VM to unaddress itself (see annex B for more information.) Table 1 Command summary Command or response message name Full name Classification 1 *RST Reset C 2 *IDN? Identify query C 3 *TST Test C 4 *TST? Test query C 5 *FLAGS? Flag query C 6 *STA
33、TUS? Status query C 7 *CMDERR? Command error query C 8 *MSG? Message register query C 9 *PIPE Pipe $C 10 *UPLOAD? Upload query $C 11 *ADDSEL Select subaddress for VM $C 12 *ATN:OPC Attention:Operation complete R 13 *ATN:CMDERR Attention:Command error R 14 *ATN:QRESP Attention:Query response R 15 *AT
34、N:PIPE Attention:Pipe $CSUP 16 *ATN Attention:Supervisor $CSUP Response of the VM: Return the *ATN:OPC response when the reset is complete. 6.2 Command name: *IDN? (identify query) Description: Query the VM for device-specific information. The format of the returned information is a list of paramete
35、r identifier names, a colon, and the actual string parameter followed by the carriage return and line feed combination (crlf). The parameters with capital letters are user-defined values. There are seven predefined return types as shown below. These must be returned with values for all seven paramet
36、ers. Use a default string value of NONE when no parameter is defined. Also, users may add custom parameters as needed. Insert these starting after the last row. Some VMs may have several associated serial numbers (SERIALNUM) or software versions (VERSION). It is the responsibility of the manufacture
37、r to clarify these possible ambiguities in the VMs user manuals. The return data structure order and form is as follows: Manufacturer:NAMEcrlf Model:MODELcrlf Device ID:DEVICEIDcrlf Serial number:SERIALNUMcrlf Software version:VERSIONcrlf SMPTE 273M-2003 Page 5 of 23 pages Virtual machine type:TYPEc
38、rlf VM subaddress:SUBADDcrlf (User defined parameters start here.) A few of the parameters require some added explanation. The DEVICEID parameter is provided by the VM as a unique number or name identifier for that VM. The DEVICEID is useful for locating devices by name, but should not be considered
39、 an address for the VM. The manufacturer should define how to set the DEVICEID value for the VM. The virtual machine type parameter, TYPE, identifies what virtual machine control dialect is used by the VM. For example, SMPTE RP 170 gives the TYPE for video tape recorders as 02. TYPE values have been
40、 defined for several different classes of equipment by SMPTE. TYPE is a string value of a HEX number. The subaddress (SUBADD) for the VM defines which VM is selected when more than one device is attached to a single TIA-232 interface port. This situation may occur whenever a multidrop, or equivalent
41、, configuration is implemented. If the VM is not configured in this fashion, use the string NONE as the address value (see 6.11 and annex B for more information.) Response of the VM: Return the ASCII string *ATN:QRESP identifier immediately followed by the data structure, with parameters, shown abov
42、e. Example: A sample returned data structure from a VTR that was issued the *IDN? command. Manufacturer:Video Things Inc crlf Model:VTI-100 crlf Device ID:VTR37 crlf Serial number:1000512A crlf Software version:2.1 crlf Virtual machine type:02crlf VM subaddress:NONE crlf 6.3 Command name: *TST TESTN
43、UM (test) Description: This command instructs the VM to execute numeric string TESTNUM. The test is run according to the manufacturers specification for that test. Test number 0 is reserved. Tests range from 1 to FFFFFF. Test number 1 instructs the VM to perform a power-on test if one exists. All ot
44、her tests are user defined. The results of each test are stored in a buffer that may be read by the *TST? command. The buffers size is not specified by this standard. Response of the VM: The VM returns a *ATN:OPC when the requested test has been executed. Example: *TST 23 (Run test number 23 and put
45、 the results in the VMs test results buffer) 6.4 Command name: *TST? (test query) Description: A query command to read the test results buffer (see *TST command). This buffer contains printable ASCII characters that describe the results from previously executed tests. The test results are retrieved
46、in a first executed, first returned basis. If the result buffer overflows as a consequence of executing too many tests, the last tests results are lost. The only way to empty the results buffer is by reading it using *TST? or issue a *RST. The actual returned data is a string (RESULT) containing the
47、 results. The string is preceded by the test number. If more than one line is needed, separate lines with a crlf combination. Test:TESTNUM:RESULT crlf Response of the VM: The response is in the form *ATN:QRESP + data structure. If there are no test results in the buffer, the returned data structure
48、is: Test:0crlf. If several different test results are in the buffer, each time *TST? is executed, the results buffer will empty another response set until finally the Test:0 response is returned. SMPTE 273M-2003 Page 6 of 23 pages Example: Assume that test numbers 4 and 7 (used here by example only)
49、 have been successfully executed using *TST. Then issuing *TST? will return the data structure (RESULT). Test:4:Power supply voltages are within range. VCC = 4.95, V12 = 11.8 crlf By issuing *TST? a second time, the returned data structure could be Test:7:Dynamic memory test passed. 512 kbytes tested. crlf A third (or more) issuing of *TST? will return Test:0 crlf (No buffered test results to return) 6.5 Command name: *FLAGS? (flag query) Description: This query returns five flags from the VM. Each flag is a string yes
