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scpi-dmm: use different Agilent SCPI command for range and measurment 

Don't use the "[SENS:]<mode>:RANGE..." request on Agilent protocol
speaking devices. Use "CONF:<mode> [<range>]" instead. This was tested
with all devices which reference this model.

In theory there is the question whether previously configured ranges
should be re-used when (exclusively) the MQ is switched. It's assumed
that this is not useful, instead users or their applications should
select the function first and optionally pick the range then. Re-use of
e.g. 10k resistance range when switching to capacitance might be seen as
confusing (and results in errors in the device).

Use the combination of INIT and FETCH? to get measurements. The READ?
request is more complex and might "undo" what INIT already initiated.
This improves perception of the 34405A meter's operation.
This commit is contained in:
Gerhard Sittig 2021-05-22 10:29:37 +02:00
parent bf03e06d57
commit b74cc88d32
2 changed files with 4 additions and 6 deletions
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5
src/hardware/scpi-dmm/api.c
View File

@ -54,12 +54,11 @@ static const struct scpi_command cmdset_agilent[] = {
{ DMM_CMD_QUERY_FUNC, "CONF?", }, { DMM_CMD_QUERY_FUNC, "CONF?", },
{ DMM_CMD_START_ACQ, "INIT", }, { DMM_CMD_START_ACQ, "INIT", },
{ DMM_CMD_STOP_ACQ, "ABORT", }, { DMM_CMD_STOP_ACQ, "ABORT", },
{ DMM_CMD_QUERY_VALUE, "READ?", }, { DMM_CMD_QUERY_VALUE, "FETCH?", },
{ DMM_CMD_QUERY_PREC, "CONF?", }, { DMM_CMD_QUERY_PREC, "CONF?", },
{ DMM_CMD_QUERY_RANGE_AUTO, "%s:RANGE:AUTO?", }, { DMM_CMD_QUERY_RANGE_AUTO, "%s:RANGE:AUTO?", },
{ DMM_CMD_QUERY_RANGE, "%s:RANGE?", }, { DMM_CMD_QUERY_RANGE, "%s:RANGE?", },
{ DMM_CMD_SETUP_RANGE_AUTO, "%s:RANGE:AUTO ON", }, { DMM_CMD_SETUP_RANGE, "CONF:%s %s", },
{ DMM_CMD_SETUP_RANGE, "%s:RANGE %s", },
ALL_ZERO, ALL_ZERO,
}; };

5
src/hardware/scpi-dmm/protocol.c
View File

@ -237,9 +237,8 @@ SR_PRIV int scpi_dmm_set_range_from_text(const struct sr_dev_inst *sdi,
is_auto = g_ascii_strcasecmp(range, "auto") == 0; is_auto = g_ascii_strcasecmp(range, "auto") == 0;
scpi_dmm_cmd_delay(sdi->conn); scpi_dmm_cmd_delay(sdi->conn);
ret = sr_scpi_cmd(sdi, devc->cmdset, 0, NULL, ret = sr_scpi_cmd(sdi, devc->cmdset, 0, NULL, DMM_CMD_SETUP_RANGE,
is_auto ? DMM_CMD_SETUP_RANGE_AUTO : DMM_CMD_SETUP_RANGE, item->scpi_func_setup, is_auto ? "AUTO" : range);
item->scpi_func_setup, is_auto ? "" : range);
if (ret != SR_OK) if (ret != SR_OK)
return ret; return ret;