Build plate cools during print I am using a Flashforge Creator Dual Extrusion 3D Printer with RepG (ReplicatorG), and tonight a print completely detached from the build plate.

I reset everything and watched it closely.   It is a simple abs print at 230/110 degrees.

A few seconds after start of print, I noticed that the print bed temp had dropped to 109... and kept dropping.

This is new behavior.  I haven't started to troubleshoot yet.  I am looking for suggestions on how to troubleshoot the issue.

Edit 1:

Tonight RepG would not connect to the printer.  I reseated the USB cord 
  and now it does.

The test print is ABS at 230/110 from this open scad.

difference()
{
    cylinder(d = 10, h = 2);
    cylinder(d = 9,  h = 2);
}


Pᴀᴜʟsᴛᴇʀ2/Oscar
  Once the print starts the print bed begins cooling.  It is cooling before 
  any filament is laid down.

Edit 2:

Examination of the gcode shows the root cause.  It does contain

M104 S230 T1 (set extruder temperature)


It does not contain a 

M109 S110 (set build plate temperature)


When I manually add the M109 to the gcode file, the model prints normally, and the build plate temperature holds for the duration of the print.  

The drop in temperature last week is due to the fact that I tend to preheat the printer before actually starting the print.  Since there was no M109 the bed plate cooled to ambient temperature.

There isn't a hardware issue here.   Most likely it is a Rep G configuration error of some sort.

Edit 3:

I resolved the issue by a fresh install of the latest Rep G.  I rebuilt the profiles from scratch with G Code to set the correct bed temp.  Thank you for your suggestions.
Your bed is obviously capable of heating up, so I would double check your cable for any kinks, cuts, blow-outs, or general connection issues both where your machine rests during warm-up and Z0 where your machine begins printing.

Most likely there is a poor connector or kinked/cut wire for the build plate.

If that doesn't appear to be the issue, I might also suggest checking your power supply. I've heard of other similar machines' power supplies not being quite strong enough to support two extruders AND a heated bed.