Bradley Smoker PLC-5 user manual Using Channel, User Mode, System Mode

10-2Communicating with Devices on a Serial Link

Configuring the Controller Serial Port

Using Channel 0

Channel 0 is the serial port and is configurable for RS-232C, RS-423, or RS-422A compatible communication. Use switch assembly SW2 to specify the serial port configuration.

To set the controller switch, see chapter 23 or look on the side label of the controller, which shows the switches in switch assembly SW2 and a table listing the settings.

You can use the controller’s serial port (channel 0) to connect the controller to devices that:

•can send and receive ASCII characters by using User mode (ASCII communication)

•communicate using DF1 protocol by using one of three available System modes

User Mode

In user mode, all data are received and sent via a buffer. To access or send this data, use ASCII instructions in your ladder program. The ASCII data a PLC-5 controller sends contain no additional protocol characters.

In user mode, only ASCII instructions can be used. If you try to use a message (MSG) instruction that references the serial port, the error (.ER) bit is set.

Examples of ASCII peripheral devices are:

•ASCII terminals

•Bar code readers

•Allen-Bradley Dataliners

•Weigh scales

•Printers

System Mode

In system mode, the controller interprets a command from another device. Use system mode when you need to communicate with other devices on a link. System mode, with DF1 protocol, is a separate and unique communication link from the DH+ link.

Publication 1785-UM012D-EN-P - July 2005