Hioki ST5520, Instruction Manual, Page: 121 / 201

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8
Communications
(RS-232C interface)
Before connecting the communication cables, thoroughly read “Usage Notes” (p. 7).
8.1 Interface Overview and Features
The communications interface can be used to control the instrument and acquire
data.
Refer to the section that is relevant to your application.
•
To control the instrument
with commands
“8.4 Controlling the Instrument and Acquiring
Data with Commands” (p. 119)
•
To create a control program
•
To acquire measured values
without using commands
“8.3 Automatically Exporting Measured Values
at the Ends of Tests (Data output function)”
(p. 117)
Communications time
•
There may be a delay in display processing depending on the frequency and nature of any
communications processing performed.
•
The data transfer time must be added when communicating with a controller.
The RS-232C transfer time can be approximated with the following formula, where the transfer
speed (baud rate) is N bps using 1 start bit, 8 data bits, no parity, 1 stop bit, for a total of 10 bits.
Transfer time T [1 character/sec.] = Baud rate N [bps]/10 [bits]
Since measured values are 11 characters in length, the transfer time for 1 piece of data is 11/T.
(Example) For a 9,600 bps connection, 11/(9600/10) = Approximately 11 ms
Output Queue and Input Buffer
Output Queue
Response messages are stored in the output queue until read by the controller. The
output queue is also cleared in the following circumstances:
•
Power on
•
Query Error
The output queue capacity of the instrument is 64 bytes. If response messages
overflow the buffer, a query error is generated and the output queue is cleared.
Input Buffer
The input buffer capacity of the instrument is 256 bytes. More than 256 bytes of data
will not be accepted.
Ensure that the no command ever exceeds 256 bytes.
8
Communications (RS-232C interface)
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1
Appx.
Ind.