Description of interface commands
Date: 15th September 2003 Valid for oscilloscopes: HM305-2, HM404, HM404-2, HM407, HM1004-2, HM1004-2A, HM1004-3, HM1505-2, HM1507, HM1507-2, HM1507-3, HM2005. RS-232 cable A 9 conductor serial interface cable (1:1 connection, i.e. without crossed pin connections ) will be required to connect the oscilloscope to an external instrument.Setting the baud rate The RS 232 interface must be initialized before use. This is effected by the first transmission of SPACE CR (20 hex., 0D hex.) after POWER UP (switching on). This will automatically set the baud rate. The following baud rates will be recognized: 110 150 300 600 1200 2400 Data transmission format: Baud Baud Baud Baud Baud Baud 4800 9600 19200 38400 56700 115200 Baud Baud Baud Baud(1.19 Baud (1.19 Baud (1.19
No parity, data length 8 bits, 2 stop bits, RTS/CTS handshake.
If the PC has a COM interface with FIFO buffer, then the maximum depth of the send buffer must be set to 8 bytes. The baud rate set will remain operative until POWER DOWN (switch off) or until the remote mode is disabled with the command ‘RM0’, or until the pushbutton LOCAL (AUTOSET button) isactivated, assuming this is not inhibited (LK=0). Once the remote mode is disabled, the data transmission can be only restored by again sending SPACE CR. If the oscilloscope does not recognize SPACE CR as first characters, or if Low-level exists on the RTS line longer than for about 2 seconds, then the oscilloscope exits the remote mode and sets the TxD Low for about 0.3s and thus generates a frameerror. The oscilloscope answers with a RETURNCODE (0 CR LF) if it has recognized SPACE CR and has set the baud rate. The scope sends ‘ESC RMLK=0’ (ESC=1B hex.) and exits the Remote state if the button LOCAL is activated in Remote-ON state. The time between the reception of the RETURNCODE Remote-OFF and Remote-ON must be at least tmin= 2*(1/Baudrate) + 60µs
Interface commands for HM305-2, HM404,HM407, HM1004-2, HM1505-2, HM1507, HM1507-2
Data transmission After successfully setting the baud rate, the oscilloscope is in Remote state and is ready to accept commands. The commands can be in capital or lower case. The commands can be divided into two basic groups: Interrogation of parameters This group of commands is distinguished by a question mark at the end of the command. When such acommand is transmitted to the scope, it answers by repeating the syntax followed by a colon and the parameters asked for. These can be binary or ASCII data depending on the command. The number of data bytes to be received is dependent on the command and can be seen from the command description. Example: Set parameter The parameters of the scope can be influenced with this command. Here commands withand without parameter can be differentiated. Example: Example: Command to the scope: Answer: Command to the scope: Answer: LK=1 RETURNCODE RES RETURNCODE Command to the scope: Answer: VERS? VERS:FC1.01 DG1.02
All commands are answered either with parameters or with a RETURNCODE in ASCII format (see description of commands). One must wait for all parameters or RETURNCODE for the previous commandbefore a new command can be sent to the scope. WORD-parameters require first the low byte and then the high byte. The setting of the scope is effected over the instrument data field (Device Data Field DDF) as binary array. Each byte of this data field can also be accessed by individual commands. The following tables show the build up of the instrument data field and the corresponding individualcommands. Definition of characters for the commands Interrogation Assign State Binary data ASCII data WORD (2 bytes) ASCII data Binary data Terminating character RETURNCODE Parameter Parameter ? = : b a w ARRAY array CR LF R x z Interrogates for parameters Set parameter Gives current parameter Data field is binary data of 1 byte Data field is ASCII data of 1 Byte Data field consists of 2 bytes...