Restoration After Transmission Errors; Flow Control; Operation With Several Devices - sauter SW 1000 Instruction Manual

5.2.6 Restoration after transmission errors

Various errors can occur during a transmission of command block or response block.
Below we present the manner in which the sound level meter treats the errors and
restores the original status.
(1) Incomplete block transmission
The four block transmission formats are specified in section 5.2.5. Immediately after
detecting an <STX> character block, the sound level meter receives subsequent data
until the <CR> and <LF> characters appear. When the data reception is complete
and the parity is correct, the sound level meter performs a final check. If the <STX>
character is received again before <CR> and <LF>, the sound level meter ignores all
the information received before and begins the block reception.
(2) Validation error
Having received a data block, the sound level meter validates the data block (except
where BCC = 00H). If the validation is incorrect, the sound level meter ignores the
instruction.
(3) Instruction error
The sound level meter probably does not recognise the instruction received, as the
computer sent an unidentified instruction or there was an unexpected error during
transmission. In case of an unexpected error, the sound level meter sends back the
NAK block containing the error code 0001H.
(4) Parameter error
The command block parameters can also contain errors: they may not be separated
by a space, exceed the available range or include an incorrect quantity of arguments.
In case of an unexpected error, the sound level meter sends back the NAK block
containing the error code 0002H.
(5) Unavailable under the current status
Incorrect operation under the current status is possible in the following cases:
A request for octave data return was received in the level meter mode or a
1
request for level meter data return was received in the octave mode.
2 A calibration request was sent during measurement.
A request for a change of measurement or system parameters was sent dur-
3
ing measurement.
In case of an unexpected error, the sound level meter sends back the NAK block
containing the error code 0003H.

5.2.7 Flow control

The sound level meter is equipped with a 3-core interface with a 6-pin P/S2 port
which does not include pins for data flow control by the hardware. The sound level
meter does not support the programmed data flow control. The correct data sent and
received can be ensured by operation in accordance with the requirements specified
in 5.2.9 Nominal parameters.

5.2.8 Operation with several devices

Using the RS-232 interface, you can interconnect several sound level meters, thus
creating a measurement network. You may change the settings of all the sound level
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