Bk-precision 5491B - Manual User Manual download pdf (Page 42)

 600

Note: Factory default baud rate is 9600.

Refer to section 4.5.2 for details on configuring baud rate settings on the multimeter.

5.2.4 Software Protocol

Please refer to the content below before programming application software.

1. For command syntax and format, refer to Chapter 6 Command Reference.

2. The controller transmits the command using the ASCII code with <LF> or <CR> as the termination

character. The multimeter executes the command after the termination character is received.

3. The character received by the multimeter will be sent back to the controller again. The controller will

not send the next character until the last returned character is received correctly from the meter. If

the controller fails to receive the character sent back from the meter, the possible reasons are listed

as follows:

 The serial interface is not connected correctly.

 Check if the same baud rate is selected for both the meter and the controller.

 When the meter is busy with executing a bus command, it will not accept any character from

the serial interface at the same time. So the character sent by controller will be ignored. In order

to make sure the whole command is sent and received correctly, the character without a return

character should be sent again by the controller.

4. The multimeter only sends information under following two conditions. The first is when a character

is received normally; the meter will send the character back as a handshake. The second is when a

query command is received; the meter will send the query response information.

5. Once a query command is received, the meter will send the query response information

immediately even if the rest of the commands have not been finished. So if the command includes

two queries, the controller should read the query responses twice. One query is recommended to be

included in a single command.

6. A query response is sent out in ASCII codes with the preset termination character.

7. For some commands that will take longer time to execute, for example reset command, the

controller should keep waiting to avoid the next command being lost when the meter is executing

the former command.

5.3 Data Format

The meter outputs the measurement results using the ASCII character string format via the RS232 serial

interface. The data format is described in the following Figure 5-3.

SD.DDDDDDESDDD<NL>

S: +/-

D: number 0 to 9

E: exponent sign (“+”is omitted)

<NL>: New Line, ASCII code is 10

Figure 5-3 Data Format

1 2 ... 37 38 39 40 41 42 43 44 45 46 47 ... 77 78

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Bk-precision 5491B - Manual User Manual Page 42