Rockwell Automation 1771-DB Basic Module User Manual - Series A - Manual (Page 96)

Operating Functions
Chapter 5
5–59
The peripheral port is used for:
1. exchanging data with an external device with user written protocol.
2. listing programs with the LIST# or LIST @ statement.
3. loading/saving programs using the 1771–SA/SB data recorders.
For these functions to operate properly and to allow flexibility for talking
to many different devices we provide parameter setup routines.
To make best use of the port, a 256 character buffer is provided on both
input and output. This means that the module may receive up to 256
characters without error from a device before the module must service the
data. The module can store an entire response to a command in the input
buffer. This is useful when the data arrives in a high speed burst that is too
fast for the BASIC program to handle character by character.
The 256 character output buffer allows the module to assemble an entire
message leaving your user program free to perform other operations while
the message is sent character by character by the device driver.
This routine sets up the parameters for the peripheral port. The parameters
set are the number of bits/word, parity enable or disable, even or odd
parity, number of stop bits, software handshaking and hardware
handshaking. Default values are:
1 stop bit
no parity
8 bits/character
DCD off
XON/XOFF disabled
1200 baud (jumper selected)
1 start bit (fixed)
5.8
Peripheral Port Support
5.8.1
Peripheral Port Support –
Parameter Set – CALL 30