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6 No-protocol Mode
6-2
CJ-series Serial Communications Units Operation Manual for NJ-series CPU Unit(W494)
6-1 Overview
Use No-protocol Mode to send and receive data using Serial Port I/O instructions (SerialSend, Serial-
Rcv, and SerialRcvNoclear) without conversion or a specific protocol. In No-protocol Mode, communi-
cations procedures, such as retry processing, data format conversion, and processing branching
according to the receive data are not performed.
No-protocol Mode enables single-directional data exchange with any general-purpose external device
with an RS-232C port or RS-422A/485 port by using the SerialSend, SerialRcv, and SerialRcvNoclear
instructions. In No-protocol Mode, it is possible to send and receive data easily, such as data input from
a bar code reader or data output to a printer.
Addition of a start code at the beginning of the data, and end code at the end of the data (or specifying
the number of receive data bytes) is possible before sending/receiving. It is also possible to control the
RS and CS and other control signals.
No-protocol Mode is supported for RS-422A/485 if the 4-wire method is used.
Additional Information
The SerialRcv instruction clears the receive buffer after it reads the receive data. The Serial-
RcvNoClear instruction does not clear the receive buffer after it reads the receive data. The Seri-
alRcvNoClear instruction is suitable for applications in which data is received consecutively at
short intervals and you do not want to miss any data.
Version Information
A Serial Communications Unit with unit version 2.1 or later, a CPU Unit with unit version 1.03 or
later, and Sysmac Studio version 1.04 or higher are required to use the SerialRcvNoClear
instruction.
6-1-1 Definition
RS-232C or RS-422A/485
General-purpose external device with serial port
(e.g, bar code reader or printer)
Serial Communications Unit
CPU Unit
SerialSend,
SerialRcv