diff --git a/cli/diag.c b/cli/diag.c
index 72c28bc3..22e22154 100644
--- a/cli/diag.c
+++ b/cli/diag.c
@@ -34,6 +34,7 @@
 #include <switchtec/endian.h>
 #include <switchtec/errors.h>
 
+#include <errno.h>
 #include <limits.h>
 #include <locale.h>
 #include <math.h>
@@ -1246,7 +1247,7 @@ static double *eye_observe_dev(struct switchtec_dev *dev, int port_id,
 	struct switchtec_status status;
 	int i, ret, first_lane, lane;
 	size_t lane_cnt[num_lanes];
-	int lane_mask[4] = {};
+	int lane_mask[5] = {};
 	double tmp[500];
 	double *pixels;
 
@@ -1391,7 +1392,7 @@ static double *eye_capture_dev_gen5(struct switchtec_dev *dev,
 				    int vstep)
 {
 	int bin, j, ret, first_lane, num_phases_l, stride;
-	int lane_mask[4] = {};
+	int lane_mask[5] = {};
 	struct switchtec_status sw_status;
 	double tmp[64];
 	double* ber_data = NULL;
@@ -1408,6 +1409,11 @@ static double *eye_capture_dev_gen5(struct switchtec_dev *dev,
 				       data_mode, eye_mode, refclk, vstep);
 	if (ret) {
 		switchtec_perror("eye_run");
+		if (errno == EBUSY ||
+		    ERRNO_MRPC(errno) == ERR_EYE_CAP_STATE_INVAL)
+			fprintf(stderr,
+				"Hint: A previous eye capture may still be in progress.\n"
+				"Wait for it to complete or reset the device.\n");
 		return NULL;
 	}
 
@@ -1489,7 +1495,7 @@ static int eye(int argc, char **argv)
 		.hstep = 1,
 		.sar_sel = 10,
 		.intleav_sel = 0,
-		.refclk = 0,
+		.refclk = 100000,
 		.data_mode = SWITCHTEC_DIAG_EYE_ADC,
 		.eye_modes_gen6 = SWITCHTEC_DIAG_EYE_FULL,
 	};
@@ -1629,6 +1635,11 @@ static int eye(int argc, char **argv)
 		return -1;
 	}
 
+	if (cfg.dev && switchtec_is_gen6(cfg.dev) && cfg.refclk == 0) {
+		fprintf(stderr, "--refclk/-r must be non-zero for Gen6 eye capture\n");
+		return -1;
+	}
+
 	if (!pixels) {
 		if (switchtec_is_gen5(cfg.dev) || switchtec_is_gen6(cfg.dev)) {
 			pixels = eye_capture_dev_gen5(cfg.dev, cfg.port_id,
diff --git a/inc/switchtec/diag.h b/inc/switchtec/diag.h
index cc3892c9..caa562e1 100644
--- a/inc/switchtec/diag.h
+++ b/inc/switchtec/diag.h
@@ -263,7 +263,7 @@ struct switchtec_gen6_diag_eye_run_in {
 	uint8_t resvd1;
 	uint8_t timeout_disable;
 	uint8_t resvd2;
-	uint32_t lane_mask[4];
+	uint32_t lane_mask[5];
 	uint8_t sar_sel;
 	uint8_t intleav_sel;
 	uint8_t vstep;
diff --git a/inc/switchtec/errors.h b/inc/switchtec/errors.h
index 5473e242..24cff7d4 100644
--- a/inc/switchtec/errors.h
+++ b/inc/switchtec/errors.h
@@ -85,6 +85,17 @@ enum {
 	ERR_ACCESS_REFUSED = 0xFFFF0001,
 	
 	ERR_PAT_MON_IS_DISABLED = 0x70b02,
+
+	ERR_EYE_CAP_LANE_MASK_INVAL = 0x70a02,
+	ERR_EYE_CAP_DEPTH_INVAL = 0x70a03,
+	ERR_EYE_CAP_TOO_MANY_LANES = 0x70a04,
+	ERR_EYE_CAP_ERROR = 0x70a05,
+	ERR_EYE_CAP_TIMEOUT = 0x70a06,
+	ERR_EYE_CAP_STATE_INVAL = 0x70a07,
+	ERR_EYE_CAP_LANE_ID_INVAL = 0x70a08,
+	ERR_EYE_CAP_BIN_NUM_INVAL = 0x70a09,
+	ERR_EYE_CAP_SUBCMD_INVAL = 0x70a0a,
+	ERR_EYE_CAP_HW_ALLOC_FAIL = 0x70a0f,
 };
 
 #endif
diff --git a/inc/switchtec/switchtec.h b/inc/switchtec/switchtec.h
index ded071c1..38964c57 100644
--- a/inc/switchtec/switchtec.h
+++ b/inc/switchtec/switchtec.h
@@ -1791,7 +1791,7 @@ int switchtec_diag_eye_set_mode(struct switchtec_dev *dev,
 				enum switchtec_diag_eye_data_mode mode);
 int switchtec_diag_eye_read(struct switchtec_dev *dev, int lane_id, int bin,
 		            int* num_phases, double* ber_data);
-int switchtec_diag_eye_start(struct switchtec_dev *dev, int lane_mask[4],
+int switchtec_diag_eye_start(struct switchtec_dev *dev, int lane_mask[5],
 			     struct range *x_range, struct range *y_range,
 			     int step_interval, int capture_depth, int sar_sel,
 			     int intleav_sel, int hstep, int data_mode,
diff --git a/lib/diag.c b/lib/diag.c
index 62b2b7dd..3d494b32 100644
--- a/lib/diag.c
+++ b/lib/diag.c
@@ -29,6 +29,9 @@
 
 #define SWITCHTEC_LIB_CORE
 #define SWITCHTEC_LTSSM_MAX_LOGS 61
+#define EYE_CAP_STATUS_TIMEOUT_MS (5 * 60 * 1000)
+#define EYE_CAP_STATUS_POLL_MS 200
+#define EYE_CAP_PROGRESS_INTERVAL 25
 
 #include "switchtec_priv.h"
 #include "switchtec/diag.h"
@@ -132,6 +135,8 @@ static int switchtec_diag_eye_status_gen5(struct switchtec_dev *dev)
 {
 	int ret;
 	int eye_status;
+	int elapsed_ms = 0;
+	int poll_count = 0;
 
 	struct switchtec_gen5_diag_eye_status_in in = {
 		.sub_cmd = MRPC_EYE_CAP_STATUS_GEN5,
@@ -146,10 +151,25 @@ static int switchtec_diag_eye_status_gen5(struct switchtec_dev *dev)
 			return -1;
 		}
 		eye_status = out.status;
-		usleep(200000);
+		usleep(EYE_CAP_STATUS_POLL_MS * 1000);
+		elapsed_ms += EYE_CAP_STATUS_POLL_MS;
+		poll_count++;
+
+		if (poll_count % EYE_CAP_PROGRESS_INTERVAL == 0)
+			fprintf(stderr, ".");
+
+		if (elapsed_ms >= EYE_CAP_STATUS_TIMEOUT_MS) {
+			fprintf(stderr, "\n");
+			errno = ETIMEDOUT;
+			switchtec_perror("Eye capture timed out waiting for completion");
+			return -1;
+		}
 	} while (eye_status == SWITCHTEC_GEN5_DIAG_EYE_STATUS_IN_PROGRESS ||
 		 eye_status == SWITCHTEC_GEN5_DIAG_EYE_STATUS_PENDING);
 
+	if (poll_count >= EYE_CAP_PROGRESS_INTERVAL)
+		fprintf(stderr, "\n");
+
 	switch (eye_status) {
 	case SWITCHTEC_GEN5_DIAG_EYE_STATUS_DONE:
 		return 0;
@@ -159,7 +179,7 @@ static int switchtec_diag_eye_status_gen5(struct switchtec_dev *dev)
 		return -1;
 	case SWITCHTEC_GEN5_DIAG_EYE_STATUS_TIMEOUT:
 		errno = ETIMEDOUT;
-		switchtec_perror("Eye capture timeout");
+		switchtec_perror("Eye capture firmware timeout");
 		return -1;
 	case SWITCHTEC_GEN5_DIAG_EYE_STATUS_ERROR:
 		errno = EIO;
@@ -191,6 +211,20 @@ static int switchtec_diag_eye_cmd_gen5(struct switchtec_dev *dev, void *in,
 				       size_t size)
 {
 	int ret;
+	struct switchtec_gen5_diag_eye_status_in status_in = {
+		.sub_cmd = MRPC_EYE_CAP_STATUS_GEN5,
+	};
+	struct switchtec_gen5_diag_eye_status_out status_out;
+
+	ret = switchtec_cmd(dev, MRPC_GEN5_EYE_CAPTURE, &status_in,
+			    sizeof(status_in), &status_out,
+			    sizeof(status_out));
+	if (ret == 0 &&
+	    (status_out.status == SWITCHTEC_GEN5_DIAG_EYE_STATUS_IN_PROGRESS ||
+	     status_out.status == SWITCHTEC_GEN5_DIAG_EYE_STATUS_PENDING)) {
+		errno = EBUSY;
+		return -1;
+	}
 
 	ret = switchtec_cmd(dev, MRPC_GEN5_EYE_CAPTURE, in, size,
 			    NULL, 0);
@@ -306,7 +340,7 @@ int switchtec_diag_eye_read(struct switchtec_dev *dev, int lane_id,
  *
  * @return 0 on success, error code on failure
  */
-int switchtec_diag_eye_start(struct switchtec_dev *dev, int lane_mask[4],
+int switchtec_diag_eye_start(struct switchtec_dev *dev, int lane_mask[5],
 			     struct range *x_range, struct range *y_range,
 			     int step_interval, int capture_depth, int sar_sel,
 			     int intleav_sel, int hstep, int data_mode,
@@ -336,6 +370,7 @@ int switchtec_diag_eye_start(struct switchtec_dev *dev, int lane_mask[4],
 			.lane_mask[1] = lane_mask[1],
 			.lane_mask[2] = lane_mask[2],
 			.lane_mask[3] = lane_mask[3],
+			.lane_mask[4] = lane_mask[4],
 			.sar_sel = sar_sel,
 			.intleav_sel = intleav_sel,
 			.vstep = vstep,
diff --git a/lib/switchtec.c b/lib/switchtec.c
index 2d843d34..717ec41f 100644
--- a/lib/switchtec.c
+++ b/lib/switchtec.c
@@ -855,6 +855,31 @@ const char *switchtec_strerror(void)
 		default: break;
 		}
 		break;
+	case MRPC_GEN5_EYE_CAPTURE:
+		switch (err) {
+		case ERR_EYE_CAP_LANE_MASK_INVAL:
+			msg = "Eye capture lane mask invalid"; break;
+		case ERR_EYE_CAP_DEPTH_INVAL:
+			msg = "Eye capture depth invalid"; break;
+		case ERR_EYE_CAP_TOO_MANY_LANES:
+			msg = "Eye capture too many lanes"; break;
+		case ERR_EYE_CAP_ERROR:
+			msg = "Eye capture error"; break;
+		case ERR_EYE_CAP_TIMEOUT:
+			msg = "Eye capture firmware timeout"; break;
+		case ERR_EYE_CAP_STATE_INVAL:
+			msg = "Eye capture state invalid (capture already in progress)"; break;
+		case ERR_EYE_CAP_LANE_ID_INVAL:
+			msg = "Eye capture lane ID invalid or inactive"; break;
+		case ERR_EYE_CAP_BIN_NUM_INVAL:
+			msg = "Eye capture bin number invalid"; break;
+		case ERR_EYE_CAP_SUBCMD_INVAL:
+			msg = "Eye capture sub-command invalid"; break;
+		case ERR_EYE_CAP_HW_ALLOC_FAIL:
+			msg = "Eye capture hardware resource allocation failed"; break;
+		default: break;
+		}
+		break;
 	default: break;
 	}