Omron CJ1W-EIP21 Operation Manuals page 250

9 FTP Server
 Setting Restrictions
The following restrictions apply to login names and passwords.
• Only single-byte alphanumeric characters can be used in the login name and password. The login
name and password are case sensitive.
• A login name consists of up to 12 characters.
• A password consists of up to 8 characters.
• Always set a password when you set a new login name. The login name will not be valid unless a
password is set for it.
• The login name is invalid if the login name is not set or characters other than single-byte alphanu-
meric characters are used.
 FTP File Transfer Mode
FTP has two file transfer modes: ASCII mode and binary mode. Before you start to transfer files, use
the type command (specifies the data type of transferred files) to select the required mode.
• To transfer a file in binary format: Select binary mode.
• To transfer a file in ASCII format: Select ASCII mode.
 Multiple Accesses to the Same File
Files accessed with the FTP server may be simultaneously accessed from multiple sources with
communications commands from other FTP servers or programming instructions. Exclusive control
is required to prevent multiple accesses. This is to prevent reading and writing the same file at the
same time. The CPU Unit automatically performs exclusive control as shown below only when the
following combinations of instructions are used. In other cases, use file operation instructions
(Change File Name, Copy File, etc.) or communications commands and perform exclusive control.
• Exclusive Control When Accessing the Same File on the SD Memory Card
Later access
Instruction
Communica-
tions command
9-4
First access
Read
Read Exclusive control is automatically
implemented and the read instruc-
tion results in an error (first-come-
first-serve).
Write Exclusive control is automatically
implemented and the write instruc-
tion results in an error (first come
first serve)
Read (Exclusive con-
trol is not
required.)
Write Implement exclusive control.
CJ-series EtherNet/IP Units Operation Manual for NJ-series CPU Unit (W495)
Instruction
Write
(Exclusive con-
trol is not
required.)
Implement
exclusive con-
trol.
Implement (Exclusive con-
exclusive con- trol is not
trol. required.)
Communications command
Read Write
Implement
exclusive con-
trol.