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Overview Section 7-1
7-1 Overview
7-1-1 Definition
No-protocol mode is a function used to send and receive data using communi-
cations port I/O instructions (TXD(236)/RXD(235) or TXDU(256)/RXDU(255))
without conversion or protocol. Therefore, in no-protocol mode communica-
tions procedures such as retry processing, data format conversion process-
ing, and processing branching according to the receive data are not
performed.
Note No-protocol mode is supported only when using a Serial Communications
Board/Unit with Unit Ver. 1.2 or later in combination with a CS/CJ-series CPU
Unit with Unit Ver. 3.0 or later. Therefore, be sure to use a CS/CJ-series CPU
Unit with Unit Ver. 3.0 or later if the no-protocol mode is required.
The no-protocol mode enables single-directional data exchange with a gen-
eral-purpose external device with an RS-232C port or RS-422A/485 port
using the TXD(236)/RXD(235) or TXDU(256)/RXDU(255) instructions. For
example, data can be sent to and received easily (with no protocol) such as
data input from a bar code reader or data output to a printer.
Note Use the TXD(236)/RXD(235) instructions for Serial Communications Boards
and the TXDU(256)/RXDU(255) instructions for Serial Communications Units.
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. The RS and CS control signals can also be controlled.
Note No-protocol mode is only supported for RS-422A/485 if the four-wire
method is used.
Serial Communications Board (unit Ver. 1.2 or later)
CPU Unit (unit Ver. 3.0 or later)
TXDU/RXDU
General-purpose external device with serial port
(e.g, bar code reader or printer)
RS-232C or RS-422A/485
RS-232C or RS-422A/485
General-purpose external device with serial port
(e.g, bar code reader or printer)
Serial Communications Unit (unit Ver. 1.2 or later)
CPU Unit (unit Ver. 3.0 or later)
TXDU/RXDU
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