From f0f8202f77a42f470f767692b22f0ad0254c038f Mon Sep 17 00:00:00 2001 From: Jan Breuer <jan.breuer@jaybee.cz> Date: 周二, 04 12月 2012 19:01:50 +0800 Subject: [PATCH] Update README - describe parameters and results handling --- README.md | 34 ++++++++++++++++++++++++++++++++++ 1 files changed, 34 insertions(+), 0 deletions(-) diff --git a/README.md b/README.md index ed3fd62..8cb57e2 100644 --- a/README.md +++ b/README.md @@ -120,3 +120,37 @@ +Implementation of command callback +------------- + +Command callback is defined as function with result of type scpi_result_t and one parameter - scpi context + scpi_result_t DMM_MeasureVoltageDcQ(scpi_t * context) + +Command callback should return SCPI_RES_OK if everything goes well. + +You can read command parameters and write command results. There are several functions to do this. + +Every time, you call function to read parameter, it shifts pointers to the next parameter. You can't read specified parameter directly by its index - e.g. + // pseudocode + param3 = read_param(3); // this is not possible + + read_param(); // discard first parameter + read_param(); // discard second parameter + param3 = read_param(); // read third parameter + +If you discard some parameters, there is no way to recover them. + +These are the functions, you can use to read parameters + - SCPI_ParamInt - read signed 32bit integer value (dec or hex with 0x prefix) + - SCPI_ParamDouble - read double value + - SCPI_ParamNumber - read double value with or without units or represented by special number (DEF, MIN, MAX, ...). This function is more universal then SCPI_ParamDouble. + - SCPI_ParamText - read text value - may be encapsuled in "" + - SCPI_ParamString - read unspecified parameter not encapsulated in "" + +These are the functions, you can use to write results + - SCPI_ResultInt - write integer value + - SCPI_ResultDouble - write double value + - SCPI_ResultText - write text value encapsulated in "" + - SCPI_ResultString - directly write string value + +You can use function SCPI_NumberToStr to convert number with units to textual representation and then use SCPI_ResultString to write this to the user. \ No newline at end of file -- Gitblit v1.9.1