If you are getting no response from a device connected to a Cyclades port you can try to reset all ports by sending HUP signal to cy_ras process:
# ps -ef | grep cy_ras
114 ? root 2908 S /bin/cy_ras
2878 ttyp1 is 1664 S grep cy_ras
# kill -1 114
114 ? root 2908 S /bin/cy_ras
2878 ttyp1 is 1664 S grep cy_ras
# kill -1 114