Syntax:

TrnPlot(sPort, nSamples, iTime, rPeriod, sTitle, AN, Tag1......Tag8, iMode, sComment, rLoScale1, rHiScale1, ......rLoScale8, rHiScale8)

Use the example below:

/* Prints a black and white plot to LPT1, containing the trend
lines of two variable tags (PV1 & PV2). The trend lines have a
starting time of 9am, on 11/10/96, 200 sample points, and a period
of 2 seconds. The trend line of PV1 will be on a vertical scale of
0-200, and PV2 will be on a vertical scale of 0-400. */

INT time;

Time = StrToDate("11/10/96") + StrToTime("09:00:00");
TrnPlot("LPT1:",200,Time,2,"Citect Trend Plot",0,"PV1","PV2","","","","","","",0,"Process variable operation
at shutdown",0,200,0,400);

-0 (AN value) is added to the TrnPlot function above which was missing in the example of the help file.