Omron CQM1H-SCB41 operation manual Overview of the Protocol Macro Functions, Section

Using Protocol Macros Section 5-1

5-1 Overview of the Protocol Macro Functions

5-1-1 Protocol Macros

The protocol macro function is used to control devices by using the PMCR(––) instruction in the ladder program to execute the data communications se- quences (protocols) with the various communications devices, such as general- purpose devices, connected to the RS-232C or RS-422A/485 port.

Standard system protocols are provided in the Serial Communications Board for controlling OMRON devices (such as Digital Controllers and Temperature Con- trollers).

Using the Protocol Support Tool called the CX-Protocol, the protocol macro function can be used to create new protocols for commercially available mea- suring instruments and devices, and to create protocols by modifying one of the standard system protocols. The standard system protocols are also provided with the CX-Protocol.

For details on the use of the CX-Protocol and the protocol macro function, refer to the CX-Protocol Operation Manual (W344).

5-1-2 Features

Wide Range of

Communications

Protocols

Customized Send and Receive Frames

Communications-related Functions

Send/Receive Monitoring

Retry Processing

PC Read/Write Variables

in Send Frames and

Receive Frames

Switch 1:N Communications or the Data Write Destinations Using Repeat Processing

PC Interrupts During Data Reception

Next Process Switching According to Receive Messages

The main features of the protocol macro functions are described below. For de- tails, refer to the CX-Protocol Operation Manual (W344).

Communications are possible with virtually any general-purpose external de- vice, provided it has an RS-232C or RS-422A/485 port, supports half-duplex communications, and supports start-stop synchronization.

Send frames (command + data and other send frames) and receive frames (re- sponse and other frames) can be created and registered according to the com- munications frame specifications of the external device.

Error check code calculations, frame length calculations during sending, and ASCII⇔ Hexadecimal conversion of numeric data are supported.

Receive wait monitoring, receive completion monitoring, and send completion monitoring are supported. If monitoring times are exceeded, either send/receive processing can be terminated or retry processing can be performed.

Send/receive retry processing can be automatically executed when an error oc- curs, simply by setting the number of retries.

Variables for reading PC memory can be included in the send frames. These can be used as destination addresses or data when reading PC data. Variables for writing to PC memory can be also included in the actual receive frames. These can be used to write the contents of destination addresses or data to the PC dur- ing reception.

Repeat processing (repeat counters) for send/receive processing can be speci- fied in communications sequences. This enables the same data to be sent by switching destination addresses during communications 1:N (N = 32 max. due to restrictions in the physical layer) or by switching the PC memory write destina- tion addresses during data reception.

An interrupt can be created in the PC’s CPU Unit during data reception, and an interrupt program can be executed in the CPU Unit.

The contents of up to 15 expected receive messages can be compared with the message actually received to determine the next process.

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