You should have the following document available when configuring devices for Modbus TCP/IP Communications:
Modicon Quantum Ethernet TCP/IP Module User Guide (840 USE 107 00)
In addition, if you are planning to send unsolicited data from a Modbus Ethernet controller, you should have the following document available:
Modicon Ladder Logic Block Library User Guide (840 USE 101 00)
VersaMaxTM System Ethernet Network Interface Unit (GFK-1860)
About Modbus TCP/IP Communications.