User`s manual

PK220038 s System Development

Serial Communication

Dynamic C has serial communication support libraries. For the Z180 port

z0 and Z180 port z1, use AASC.LIB, Z0232.LIB, and Z1232.LIB. For

RS-232 expansion cards that interfaced through the PLCBus on the

PK2200, use EZIOPLC.LIB.

Functional support for serial communication includes the following:

 Initialization of the serial ports

 Monitoring, and reading, a circular receive buffer

 Monitoring, and writing to, a circular transmit buffer

 An echo option

 CTS (clear to send) and RTS (request to send) control for

RS-232.

 XMODEM protocol for downloading and uploading data

 A modem option

The PK2200 can be configured for either two RS-232

channels or one RS-232 and one RS-485. Z0 is RS-232

only and Z1 may be configured for RS-232 or RS-485.

See Chapter 3 for information on configuring the serial

communication channels.

Z180 Port Z0 is configured at the factory for RS-232

and Port Z1 is configured for RS-485.

Receive and Transmit Buffers

Serial communication is made easier with a background interrupt routine

that updates receive and transmit buffers. Every time a port receives

another character, the interrupt routine places it into the receive buffer. A

program can read the data one character at a time or as a stream of

characters terminated by a special character.

A program sends data by writing characters into the transmit buffer. If the

serial port is not already transmitting, the write functions automatically

initiate the transmission. Once the last character of the buffer is sent, the

transmit interrupt is turned off. Data can be written one character at a

time or as a stream of characters.