ProSoft Technology MVI71-GSC - Manual (Page 61)

Reference MVI71-GSC ♦ PLC Platform
Generic Serial Communication Module
ProSoft Technology, Inc. Page 61 of 82
January 31, 2008
Read-Write Devices
Read-write devices are those that both send and receive data. An example of
this type of device is a terminal. A terminal will send data entered on the
keyboard out its serial port and display any data received on its port on the
monitor. All data received from the terminal will be routed to the PLC processor
through the MVI71-GSC's BTR blocks. Data to be written to the terminal will be
sent to the module using the BTW blocks. The module will send new data in the
BTW block out the application port to the terminal. The example shipped with the
module (MVI71GSC_xx.ACD) can be interfaced with a terminal to echo back all
characters received. The data flow diagram for a read-write device is shown
below:
5.1.11 Termination of Received Data
When data is received on either of the application ports, you must define in the
configuration when this data will be transferred to the PLC processor. Within the
module, this is known as the termination type for port. When the termination
condition is met, the data will be sent from the port's receive buffer (data area of
4096 bytes) to the processor using a read block. This termination type is set in
the bit mapped, Type field of the module object. The following illustration shows
the bit map used for this parameter.