X-Git-Url: https://sigrok.org/gitweb/?p=libsigrok.git;a=blobdiff_plain;f=src%2Fhardware%2Fhp-3478a%2Fapi.c;h=1fd3ff203ad7a872fa451a7361fc1485d277a019;hp=f9419a6e09ced36fb7625a24990b2a50ae4387e4;hb=8ef4fb3347830023b80a5e121c7ffd66e10f4944;hpb=0e3c3c80b86b7ea7590225186953ea0c4d603613

diff --git a/src/hardware/hp-3478a/api.c b/src/hardware/hp-3478a/api.c
index f9419a6e..1fd3ff20 100644
--- a/src/hardware/hp-3478a/api.c
+++ b/src/hardware/hp-3478a/api.c
@@ -129,6 +129,14 @@ static struct sr_dev_inst *probe_device(struct sr_scpi_dev_inst *scpi)
 	struct sr_dev_inst *sdi;
 	struct dev_context *devc;
 
+	/*
+	 * The device cannot get identified by means of SCPI queries.
+	 * Neither shall non-SCPI requests get emitted before reliable
+	 * identification of the device. Assume that we only get here
+	 * when user specs led us to believe it's safe to communicate
+	 * to the expected kind of device.
+	 */
+
 	sdi = g_malloc0(sizeof(struct sr_dev_inst));
 	sdi->vendor = g_strdup("Hewlett-Packard");
 	sdi->model = g_strdup("3478A");
@@ -152,6 +160,14 @@ static struct sr_dev_inst *probe_device(struct sr_scpi_dev_inst *scpi)
 
 static GSList *scan(struct sr_dev_driver *di, GSList *options)
 {
+	const char *conn;
+
+	/* Only scan for a device when conn= was specified. */
+	conn = NULL;
+	(void)sr_serial_extract_options(options, &conn, NULL);
+	if (!conn)
+		return NULL;
+
 	return sr_scpi_scan(di->context, options, probe_device);
 }