Omron V680S-HMD64-EIP User Manual page 287

 Mutual Interference of RF Tags
If you use more than one RF Tag, separate them by at least the interval shown below to prevent
malfunctions due to mutual interference.
If the distance between the RF tags is too short, read / write distance will be reduced.
 V680S-HMD64-EIP Reader/Writer
 V680S-HMD66-EIP Reader/Writer
130 mm min.
130 mm min.
150 mm min.
150 mm min.
130 mm min.
130 mm min.
150 mm min.
150 mm min.
Section 11
Appendices
RFID System
285
User's Manual
(EtherNet/IP TM )