User's Manual

7 Modbus/TCP Communications
7 - 14
UHF RFID System V780-series Reader/Writer User’s Manual (Z389)
If you want to check the EPC code or reception level when communications with the RF Tag are suc-
cessful, send a GET RF TAG ADDITIONAL INFORMATION command after the response to the com-
munications command has been received. The reception level from the RF Tag that was just
communicated with will be returned.
With an expanded command, the maximum size of data that you can read from an RF Tag is 2,048
words.
If an error occurs in the RF Tag communications, the error code is returned with the response. No addi-
tional command is required to check the error code.
You can also specify a command option to have the EPC code or reception level returned with the other
data.
When you send an RF Tag communications command with multiaccess communications, the
Reader/Writer communicates with more than one RF Tag in the communications field.
The Reader/Writer will communicate with all of the RF Tags in the communications field within the com-
munications timeout time (64 max.) and then return a response.
Using an Expanded Command (FC100)
7-4-4 RF Tag Communications Command Procedure for Multiaccess
Communications
Host device
(client)
Reader/Writer
(server)
RF Tag A
Command
execution
READ DATA communications
command sent.
Communications field
RF Tag memory
read/written.
GET RF TAG ADDITIONAL
INFORMATION command sent.
Reception level
Response returned.
Response returned.
Host device
(client)
Reader/Writer
(server)
RF Tag A
Command
execution
EXPANDED DATA READ
communications command sent.
Communications field
RF Tag memory
read/written.
Error code
+ EPC code
+ Reception level
Read data (2,048 words max.)
Response returned
(2,048 words max.)