Chapter 8 - Using MS-DOS
PL-5910 Series User Manual
8-21
8.1.4 Serial Port Driver(EXTCOM.SYS )
The Panel Computer (PL) unit's RS-232C BIOS (INT 14h) has been enhanced and
uses reception interrupt when transmitting data. (Can be used like a Windows®PC
standard function) As a result, this software does not need to be installed when an
application for controlling the serial port directly is used, or when Windows is running.
- A Port Base Address: Reception Buffer Size (unit = KB)
The Port Base Address, or the Reception Buffer Size can be designated here. Param-
eters for up to four ports can be entered, using the predefined Port numbers of 0 to 3
(COM1 to COM).
Port Base Address Table
- N Designates the ports not used by EXTCOM.SYS.
Ex.) When port 1 is not to be used by EXTCOM.SYS;
DEVICE = EXTCOM.SYS -A3F8:1 -N -A3E8:1 -N can be used.
• -A and -N recognize Port numbers based on the positions designated for them.
• When DEVICE = EXTCOM.SYS is entered, all ports are used by EXTCOM.SYS.
With the PL-5910 series units, normally port number 3 (COM4) can not
be used. As a result, be sure to designate all the unit's ports in this
statement.
Ex.) DEVICE = EXTCOM.SYS -A3F8:1 -N -A3E8:1 -N -M
Port Number
Port Base
Address
Interrupt Device
Level
Description
0
3F8h
IRQ4
COM1 RS-232C (SIO1)
1
2F8h
IRQ3
COM2 RS-232C (SIO2)
2
3E8h
IRQ11
COM3 RS-485 Multidrop
Connection Possible
3
2E8h
IRQ10
COM4 Reserved for T ouch
Panel (Not available to User)
• -M is used when Port 2 (COM3:RS-485) is used for a Multi-Drop connection. When
this port is designated for Multi-Drop, startup is performed with DTR set to "OFF"
(unable to transfer data).
