scpi-dmm: Gracefully handle meters that lack OPC command.

[libsigrok.git] / src / hardware / scpi-dmm / protocol.c

diff --git a/src/hardware/scpi-dmm/protocol.c b/src/hardware/scpi-dmm/protocol.c
index d8d07957f3f5ac3926cacba121d764fa207106eb..fe20441408fa39b1c43fbdd9ab82ce0676a39c26 100644 (file)
--- a/src/hardware/scpi-dmm/protocol.c
+++ b/src/hardware/scpi-dmm/protocol.c
@@ -28,7 +28,9 @@ SR_PRIV void scpi_dmm_cmd_delay(struct sr_scpi_dev_inst *scpi)
 {
        if (WITH_CMD_DELAY)
                g_usleep(WITH_CMD_DELAY * 1000);
-       sr_scpi_get_opc(scpi);
+
+       if (!scpi->no_opc_command)
+               sr_scpi_get_opc(scpi);
 }
 
 SR_PRIV const struct mqopt_item *scpi_dmm_lookup_mq_number(
@@ -170,6 +172,7 @@ SR_PRIV int scpi_dmm_get_meas_agilent(const struct sr_dev_inst *sdi, size_t ch)
        int sig_digits, val_exp;
        int digits;
        enum sr_unit unit;
+       double limit;
 
        scpi = sdi->conn;
        devc = sdi->priv;
@@ -282,9 +285,10 @@ SR_PRIV int scpi_dmm_get_meas_agilent(const struct sr_dev_inst *sdi, size_t ch)
        }
        if (!response)
                return SR_ERR;
-       if (info->d_value > +9e37) {
+       limit = 9e37;
+       if (info->d_value > +limit) {
                info->d_value = +INFINITY;
-       } else if (info->d_value < -9e37) {
+       } else if (info->d_value < -limit) {
                info->d_value = -INFINITY;
        } else {
                p = response;
@@ -456,9 +460,12 @@ SR_PRIV int scpi_dmm_get_meas_gwinstek(const struct sr_dev_inst *sdi, size_t ch)
        }
        if (!response)
                return SR_ERR;
-       if (info->d_value > +9e37) {
+       limit = 9e37;
+       if (devc->model->infinity_limit != 0.0)
+               limit = devc->model->infinity_limit;
+       if (info->d_value >= +limit) {
                info->d_value = +INFINITY;
-       } else if (info->d_value < -9e37) {
+       } else if (info->d_value <= -limit) {
                info->d_value = -INFINITY;
        } else {
                p = response;
@@ -494,10 +501,9 @@ SR_PRIV int scpi_dmm_get_meas_gwinstek(const struct sr_dev_inst *sdi, size_t ch)
        case 7:
        case 16:
                /* In resitance modes 0L reads as 1.20000E8 or 1.99999E8. */
+               limit = 1.2e8;
                if (strcmp(devc->model->model, "GDM8255A") == 0)
                        limit = 1.99999e8;
-               else
-                       limit = 1.2e8;
                if (info->d_value >= limit)
                        info->d_value = +INFINITY;
                break;