I have a large data file with a good 30,000 entries so far.

Upon plotting the data, I hit a problem.

I have a column with the date in and a column with the time in...

Format: Date: 03/05/2015 (dd/mm/yyyy) Time: hh:mm:ss

When combined as 03/05/2015 08:40:03 for all entries, when plotting, the chart ignores any gaps in the data (chronologically). I want this to be as a data vs time chart with any gaps in data recording being shown.

I ahve included a copy+paste here to show my data with a "data blip" where the unit has restarted due to a problem/bug.

UNIX TIME Date Time H1 T1 H2 T2 Light Data entry ID
UNIXTIME              Date          Time        H1    T1     H2    T2   Light Entry ID

1430732069	04/05/2015	09:33:59	44.7	19.1	49.4	26.1	345	3071
1430732098	04/05/2015	09:34:29	45.3	19.3	48.9	26.4	313	3072
1430732128	04/05/2015	09:34:58	49	19.6	45.1	26.8	384	3073
1430732157	04/05/2015	09:35:27	44.6	19.7	41.2	26.5	433	3074
1430732186	04/05/2015	09:35:56	40.7	19.7	36.6	25.8	464	3075
1430732215	04/05/2015	09:36:26	43.8	19.7	38.3	25	498	3076
1430732244	04/05/2015	09:36:55	40.7	19.2	36.2	23.7	353	3077
1430732274	04/05/2015	09:37:24	40.4	18.8	35.1	23.1	437	3078
1430732303	04/05/2015	09:37:53	42.1	18.5	37	22.4	326	3079
1430732917	04/05/2015	09:48:08	48.7	18.4	47.7	20.1	331	1
1430732946	04/05/2015	09:48:37	46.1	18.4	44.6	20	330	2
1430732975	04/05/2015	09:49:06	46	18.5	47.2	19.9	337	3
1430733005	04/05/2015	09:49:35	45.4	18.7	43.4	20.3	333	4
1430733034	04/05/2015	09:50:04	42.3	18.7	41.1	20.2	326	5
1430733063	04/05/2015	09:50:33	43.8	18.5	42.6	19.9	316	6
1430733092	04/05/2015	09:51:03	45	18.5	42.5	20.1	305	7
1430733122	04/05/2015	09:51:32	46.2	18.4	43.6	19.8	293	8
1430733151	04/05/2015	09:52:01	45.5	18.3	45.5	19.9	288	9
1430733180	04/05/2015	09:52:30	45	18.4	46.7	20.5	282	10
Thanks! Find it a bit odd excel can not simply see a very common date+time scenario and know what you want...