Remote Control 
  Copyright © Itech Electronic Co., Ltd.  6 
Message exchange protocol 
Two rules summarize the message exchange protocol: 
  Rule  1.You  must  always  tell  the  IT6800A/B  Series  what  to  send  to  the 
computer. 
The following two steps must always be performed to send information from the 
instrument other computer: 
1. Send the appropriate query command(s) in a program message.1. 
2. Address the IT6800A/B Series to talk. 
  Rule 2.The complete response message must be received by the computer 
before another program message can be sent to the IT6800A/B Series. 
1.6 Command Format 
Formats for command display are as follows: 
[SOURce[1|2]:]VOLTage:UNIT {VPP|VRMS|DBM} 
[SOURce[1|2]:]FREQuency:CENTer 
{<frequency>|MINimum|MAXimum|DEFault} 
Based on the command syntax, most commands (and certain Parameter) are 
expressed in both upper and lower cases. Upper case refers to abbreviation of 
commands. Shorter program line may send commands in abbreviated format. 
Long-format commands may be sent to ensure better program readability.   
For example, both formats of VOLT and VOLTAGE are acceptable in the above 
syntax statements. Upper or lower case may be used. Therefore, formats of 
VOLTAGE, volt and Volt are all acceptable. Other formats (such as VOL and 
VOLTAG) are invalid and will cause errors. 
  Parameter options with given command strings are included in the brace 
({ }). The brace is not sent along with command strings. 
  Vertical stripes (|) separate several parameter options with given command 
strings. For example, {VPP|VRMS|DBM} indicates that you may assign 
"APP", "VRMS" or "DBM" in the above commands. Vertical stripes are not 
sent along with command strings. 
  Angle brackets (< >) in the second example indicates that a value must be 
assigned to the parameter in the brace. For example, the parameter in the 
angle bracket is <frequency> in the above syntax statements. Angle 
brackets are not sent along with command strings. You must assign a 
value (such as "FREQ:CENT 1000") to the parameter, unless you select 
other options displayed in the syntax (such as "FREQ:CENT MIN"). 
  Some syntax elements (such as nodes and Parameter) are included in 
square brackets ([ ]). It indicates that these elements can be selected and 
omitted. Angle brackets are not sent along with command strings. If no 
value is assigned to the optional Parameter, the instrument will select a 
default value. In the above examples, "SOURce[1|2]" indicates that you 
may refer to source channel 1 by "SOURce" or "SOURce1" or "SOUR1" or 
"SOUR". In addition, since the whole SOURce node is optional (in the 
square bracket), you can refer to the channel 1 by omitting the whole 
SOURce node. It is because the channel 1 is the default channel for 
SOURce language node. On the other hand, if you want to refer to channel 
2, "SOURce2" or "SOUR2" must be used in the program line.