CAN TPDO send rate

I am trying to get encoder values from my FLB2360 to my application at a 1 ms interval using the CAN bus. My initial design was to copy the encoder data into VAR 9/10 using a Micro Basic script with the controller configured to output TPDO 1 at a 1 ms send rate (TPDO 2-4 defaulted to 0 ms). Before implementing the script, I did some timing analysis of the TPDO 1 output rate. Instead of the expected 1 ms/frame inside my application, I am seeing ~4 ms/frame. If I choose a TPDO 1 send rate of 10 ms, I see around 12-13 ms/frame. Is this expected? I am not using a CAN bus sniffer, just O/S clock function calls to do the timing measurement. The micro-controller to capture the frames is a BeagleBone Black with a simple CANOpen test program to read the frames.

Is this also a limiting factor for RPDO messages going into the controller? If I send an RPDO message from my application at 1 ms will the controller see them at that rate?