3-22
int86(0x21,®s,®s);
}
3.2. Communication Environment Setup
Before placing MR350MKII into the communication environment, you have
to decide:
1) Whether the RS-422/485 port or RS-232 port assigned as host port and
another one as serial port.
2) Set communication protocol for host port. Please note, the protocol for
serial port is always none.
3) If you have installed a internal modem interface. You have to set COM1 as
modem instead of RS485.
The factory defaults for the communication environment are:
Host port: as RS-422/485, multi-point protocol.
Serial port: RS-232, none protocol.
Once you have assigned the protocol to the host port, the MR350MKII’s
system kernel will automatically packing or unpacking the sending or
receiving data according to the selected protocol. On the other hand, since
the serial port has no protocol, you must use INT 34H (RS232) or INT 33H
(RS-422/485) to read or write data character by character.
??NOTE:
If you want to control the host port I/O service, you must designate
“NONE” protocol for the host port and then using INT 34H or INT 33H to
control I/O for RS232 or RS422/485. The proper function call depends on
which port is assigned as host port(see the next two sections).
1C Select COM1 or COM2 as the host port
Entry Parameters: AH = 1C
BH = 0
AL = 1 ; Select COM1 as host
2 ; Select COM2 as host
Returned Value: None
??NOTE:
While one of the COM port is designated as host, the other one is set as
serial port automatically by system.