ST1952 Operation Manual
35
Before you choose a baud rate, make sure the programming terminal that you are connecting to the
ST1952 can support the baud rate you selected. Both the multimeter and the other device must be
configured for the same baud rate.
Perform the following steps to select a baud rate:
1. Press
Shift
→
to enter the menu on the menu level and use
or
key to move
across to “C: SYS MEU”. Press
key to enter into the Baud command and use
or
key
to select “2:BAUD RAT” and press
key to enter into the baud parameter setting, “BAUD:
<rate>” is displayed.
2. Use
or
key to select a baud rate and then press
to confirm the selection.
3. Press
Shift
+
key to exit from the menu and return to the measurement status.
D. Software Protocol
Since the hardware handshaking lines CTS and RTS are not used by ST1952, the multimeter uses the
character return method to decrease the data losses and errors during communication. Please refer to
the content below before programming communication 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> as the terminal character.
ST1952 executes the command after the terminal character is received.
3. The character received by ST1952 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 ST1952. If the
controller fails to receive the character sent back from ST1952, the possible reasons are listed as
follows:
The serial interface is not connected correctly.
Check if the same baud rate is selected for both ST1952 and the controller.
When ST1952 is busy with executing a bus command, ST1952 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. ST1952 only sends information under following two conditions. The first is when a character is
received normally; ST1952 will send the character back as a handshake. The second is when a
query command is received; ST1952 will send the query response information.
5. Once a query command is received, ST1952 will send the query response information immediately
even if the rest 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 terminal character.
7. Several query responses will be sent continuously with 1ms interval. The controller should be ready
to receive the responses; otherwise the response information will be lost.
8. The controller should receive the query response terminal character. Otherwise you will confuse a
terminal character with a returned character. At the same time the controller should receive the last
returned character before receiving a query response.
9. For some commands that will take a long time to execute, for example reset command, the
controller should keep waiting to avoid the next command being lost when ST1952 is executing the
