NOVA541
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5-4. Standard Protocol
▪ The standard protocol of NOVA series is composed of ASCII string. A user can read or write the
contents of D-Register.
▪ There are two kinds of protocols which can be selected by COM.P parameter.
▪ The frame of standard protocol starts with STX and ends with CR LF.
▪ 'SUM' protocol (COM.P = 1) is a more sophisticated one which includes Check Sum as an error
check.
① The Frame structure of standard protocol
STX
Address
Command
Data
CR
LF
0x02
1~99
Refer to each command
0x0D
0x0A
② The Frame structure of the SUM protocol
STX
Address
Command
Data
SUM
CR
LF
0x02
1~99
Refer to each command Check Sum
0x0D
0x0A
▪ Check Sum is calculated as following.
1) Add the ASCII code of characters from the character next to STX one by one up to the
character prior to SUM.
2) Represent the lowest one byte of the sum as a hexadecimal notation (2 characters).
5-4-1 Communication command
▪ There are several kinds of commands, general commands for read/write of D-register,
information command for checking the controller version, and check command for inspection
procedure.
① General Command
Command
Function
RSD
D-Register Sequential Read
RRD
D-Register Random Read
WSD
D-Register Sequential Write
WRD
D-Register Random Write
STD
D-Register Monitoring Set
CLD
D-Register Monitoring Call