User's Manual

7 Modbus/TCP Communications
7 - 12
UHF RFID System V780-series Reader/Writer User’s Manual (Z389)
Precautions for Correct Use
Access to a Reader/Writer is possible from only one host device at a time.
If a host device B connects to a Reader/Writer while another host device A is already con-
nected to it, the connection between host device A and the Reader/Writer will be automatically
disconnected and a connection with host device B will be established.
If an error response is received, you can check the most recent command error information or com-
mand error log in the Reader/Writer to get details on the nature of the error. An error has occurred if the
function code in the response that was returned from the Reader/Writer is 80 hex higher than the func-
tion code in the query.
You can do this by sending a GET MOST RECENT ERROR INFORMATION command or GET COM-
MAND ERROR LOG command from the host device or by using the Web browser interface through the
Web server.
7-4-2 Error Response Reception Procedure
Error
occurs.
Error
detected.
Host device
(client)
Reader/Writer
(server)
Command
execution
GET MOST RECENT ERROR
INFORMATION command sent.
(Or, GET COMMAND ERROR LOG command sent.)
Error information returned.
Command sent.
Response returned.
Function code + 80 hex