Caution Issuance for APC Smart UPS: Use of industry standard serial cables may drop load
We have stumbled upon a load drop risk for APC SmartUPS users. Do not use a null modem, nor straight thru cable between a PC serial port and the UPS. The UPS may shut down as soon as the connection is made and drop the load. The pin out of the cable required is different than standard cables. We found this problem repeatable and online research shows it is not unique to the unit we found it on. Due to good fortune we found this in-house while setting up a demo of our monitoring equipment and the UPS did not have load on it at the time. We found the load dump to occur with both a straight thru cable and a null modem cable.