Changing DB9 Gender: Crossover or Straight?
The only way to be sure is to measure the voltage on pins 2 and 3 with a multimeter while the device is powered up, but otherwise idle. The pin that is functioning as an output (regardless of whether it is called "Transmit" or "Receive") will have a definite negative bias on it (anywhere from -5V to -12V typically), while the pin that is functioning as an input will be close to 0V.

Connect the input pin of the device to pin 2 of the PC (or USB to RS-232 adapter), and connect the output pin to pin 3.



After looking at Table 9 in the manual, I think that the description of the two cables strongly hints that the device is DCE, which means that you'll need a straight-through cable.