Parallel Port (LPT PORT) 8 Channel Relay Board | Circuit Ideas I Electronic DIY Projects I Robotics
RS232 Relay Board 2CH DC 12V/24V Serial Port Switch Module for PLC Motor LED PTZ | eBay
Parallel Port Relay Board Kit - CK1601 | Electronic Kits
R223C16 16-Channel Relay Board DB9 Relay Module Female Interface Serial Port Smart Module for Parallel Industrial Electronics: Amazon.com: Industrial & Scientific
2 Channel Serial Port Relay Module DC 12V PC Computer USB RS232 DB9 RS485 UART Remote Control Switch Board For Smart Home From Isyour, $28.98 | DHgate.Com