Configuring a Controller
372 SPU 780 01EMAN May 2002 81
Simple ASCII
Ports Some Modicon controllers have RS-232 ports as part of Remote I/O drops.
Advanced programmers can use these ports (called simple ASCII or ASCII/DAP
ports), for serial communications between controllers and data terminal equipment.
In ladder logic, use the Block Move (BLKM) instruction to send and receive Simple
ASCII messages. Configure the number of ASCII ports for a controller by setting th e
ASCII Ports parameter in the General tab.
The 984A, 984B, and Micro 311, 411, 512, 612 controllers have simple ASCII ports
having fewer properties than Modbus ports:
Parameters Description
Parity Adds a check bit to a packet to make the number of binary ones always
either odd (Odd Parity) or even (Even Parity). If parity is set to None,
the check bit is not added. The PC and controller must use the same
parity setting. Default is even.
Stop/Data Sets the number of bits at the end of a packet which prepare the
receiving device for the next packet. The PC and controller must use
the same number of stop bits. Default is 1.
Baud Sets the data transfer speed of the controller’s Modbus port in bits per
second. The PC and controller must be set to the same baud. Default
is 9600.