The KRC1 includes a DeviceNet Master port, yes. Any standard DeviceNet Slave device can be connected to the robot using this port.
The process of controlling the motor from the robot depends entirely on what signals the frequency drive needs. You will need to obtain the interface information for the frequency driver and allocate signals in IOSYS.INI and CONFIG.DAT to support those requirements.
For example, the drive might need a Start signal, and a Fault Reset signal, and an 8-bit signal for speed control. So in CONFIG.DAT you might use:
SIGNAL VFD_START $OUT [89]
SIGNAL VFD_FAULT_RESET $OUT [90]
SIGNAL VFD_SPEED_OUT $OUT [97] TO $OUT [104] ; 8bit integer
SIGNAL VFD_FAULT $IN [90] ; fault input from VFD
Then, your program might work something like:
WHILE VFD_FAULT
PULSE (VFD_FAULT RESET, TRUE, 0.1) ; send fault-reset to VFD
WAIT SEC 0.2 ; wait for fault to clear
ENDWHILE ; keep looping until fault is cleared
VFD_SPEED_OUT = 128 ; 50% of 8-bit speed value
WAIT SEC 0.1 ; signal settling time
VFD_START = TRUE ; start motor
This is all very bare-bones, of course.