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Pascal Communications Library ( PCL )
for Turbo Pascal 4.0 through 6.0
USER REFERENCE MANUAL
Version 1.0
20 May 1991
Copyright (C) 1991
By MarshallSoft
All rights reserved
MarshallSoft
PO Box 4543
Hunstville, AL 35815
(205) 881-4630
Page 1
Table of Contents
Chapter Page
Introduction.................................3
Registration.................................4
Serial COM Ports.............................5
RS232........................................6
National INS8250 UART........................7
Revision History.............................7
Warranty.....................................7
Using the Library............................8
Compiling.................................9
Problems.................................10
Library Reference...........................11
SioBaud..................................12
SioBrkKey................................13
SioBrkSig................................14
SioCrtWrite..............................15
SioDTR...................................16
SioDelay.................................17
SioDone..................................18
SioError.................................19
SioGetc..................................20
SioKeyPress..............................21
SioKeyRead...............................22
SioLine..................................23
SioModem.................................24
SioParms.................................25
SioPutc..................................26
SioRTS...................................27
SioReset.................................28
SioRxBuf.................................29
SioRxFlush...............................30
SioRxQue.................................31
SioTimer.................................32
SioUnGetc................................33
Function Summary............................34
Error Code Summary..........................35
Page 2
Introduction
The Pascal Communications Library ( PCL ) is an asynchronous
communications library designed for experienced software
developers programming in Turbo Pascal ( version 4.0 and up). An
IBM PC/XT/AT or compatible is required. The PCL features:
o 16 communications functions + 6 support functions.
o Receiver is interrupt driven.
o Runs from 300 baud to 115,200 baud.
o Supports COM1, COM2, COM3, and COM4.
o Adjustable receive queues from 8 bytes to 16 KB.
o Control-BREAK error exit.
o 11 comm error conditions trapped.
o Allows 2 ports to run concurrently.
o Complete modem control & status.
o Written in hand optimized assembly language.
o Low overhead & very reliable !
A typical application program using PCL might look like the
following code outline:
+----------------------------------------------------------------+
| program YourProgram |
| uses PCL; |
| ... |
| ... |
| var Buffer : array[0..1023] of Char; |
| ... |
| begin (* YourProgram *) |
| RetCode := SioRxBuf(Port,Buffer,Size1024); |
| RetCode := SioParms(Port,NoParity,OneStopBit,WordLength8); |
| RetCode := SioReset(Port,Baud2400); |
| ... |
| ... ( application code ) |
| ... |
| RetCode := SioDone(Port); |
| end. (* YourProgram *) |
+----------------------------------------------------------------+
A simple terminal emulator program CALLPGM.C is provided in source
code form as an example of the use of PCL functions. CALLPGM can
be used to call up bulletin board services or mainframe computers.
If you find any problems with the Pascal Communications Library
or have any suggestions for improvement, please call or write. A
C language version of PCL ( called CCL ) is available.
Custom versions of PCL can be developed for special needs. Custom
communication packages can also be developed. Call for prices.
Page 3
Registration
The shareware version of PCL.LIB is provided so that you may
personally determine the usefulness of the product for yourself.
If you can use PCL, please register your use with us.
MarshallSoft
PO Box 4543
Huntsville, AL
35815-4543
Please pay by check in US dollars. Payment must accompany
purchase orders. Print the file PCL.INV if an invoice is needed.
The registered package is $35 postpaid and includes:
o PCL.PAS PCL Unit.
o PCL_LIB.ASM PCL library source code.
( without the shareware screen )
o PCL.DOC PCL User Reference Manual.
o Backbone bound printed User Reference Manual.
o Telephone support for one year.
o All future updates are $10
PCL_LIB.ASM is the source code for the library. The source code is
copyrighted by MarshallSoft. The user is granted a license to use
the PCL object code in his own application only. PCL_LIB.ASM is
not shareware and may not be sold or given away to anyone.
The registered user will receive the latest version of PCL by
return mail. A 5.25" diskette is provided unless a 3.5" diskette
is requested when ordering.
Page 4
Serial COM Ports
IBM PC compatible computers can have up to four serial ports. The
BIOS table located at address 40:0000 has room for four
communication port addresses: COM1 to COM4. During boot up, the
COM1 and COM2 addresses are placed in the BIOS table providing
that the hardware is present. Unfortunately, the COM3 and COM4
addresses are not placed in the table in DOS through version 3.3.
This can be corrected by using DEBUG to assemble the following
program SETCOM3 which should be added to the AUTOEXEC.BAT file.
When executed, this program will place the standard COM3 port
address 03E8 in the BIOS table. For COM4, change 03E8 to 02E8 and
[0004] to [0006].
PUSH DS
MOV AX,0040
MOV DS,AX
MOV AX,03E8
MOV [0004],AX
POP DS
MOV AX,4C00
INT 21
Please note that you must have the physical hardware present !
Page 5
RS-232C
RS-232 is the name of the serial data interface standard used to
connect computers to modems. Most IBM compatible computers are
built with at least one serial port and use either DB9 ( 9 pin )
or DB25 ( 25 pin ) connectors.
A summary of these pins and their function follows. For more
detailed information, refer to one of the many books dealing with
RS-232 interfacing.
Signal Ground Pin 7 (DB25), Pin 5 (DB9)
The SG line is used as the common signal ground, and must always
be connected.
Transmit Data Pin 2 (DB25), Pin 3 (DB9)
The TX line is used to carry data from the computer to the modem.
Receive Data Pin 3 (DB25), Pin 2 (DB9)
The RX line is used to carry data from the modem to the computer.
Data Terminal Ready Pin 20 (DB25), Pin 4 (DB9)
The DTR line is used by the computer to signal the modem that it
is ready.
Data Set Ready Pin 6 (DB25), Pin 6 (DB9)
The DSR line is used by the modem to signal the computer that it
is ready.
Request to Send Pin 4 (DB25), Pin 7 (DB9)
The RTS line is used to "turn the line around" in half duplex
modems, but is not necessary in full duplex modems.
Clear to Send Pin 5 (DB25), Pin 8 (DB9)
The CTS line, like the RTS line, in not necessary in full duplex
modems.
Data Carrier Detect Pin 8 (DB25), Pin 1 (DB9)
The DCD line is used by the modem to signal the computer that a
data carrier signal is present.
Ring Indicator Pin 22 (DB25), Pin 9 (DB9)
The RI line is asserted when a 'ring' occurs.
Page 6
National INS8250
The Pascal Communications Library is based on the standard
National INS8250 UART. The 8250 consists of 6 register ports
based at the following standard addresses:
COM1 = 3F8H COM2 = 2F8H COM3 = 3E8H COM4 = 2E8H
If you are not familiar with the INS8250, several good books are
available. Although a knowledge of the 8250 is not necessary to
use PCL, a general knowledge of the theory of operation of
Univeral Asynchronous Receiver / Transmitters ( UARTs ) is
recommended.
Offset R/W Register
0 R/W Receiver ( read ) / Transmitter ( write )
1 R/W Interrupt Enable
2 R Interrupt Identification
3 R/W Data Format ( Line Control )
4 R/W RS-232 ( Modem ) Control
5 R/W Line Status
6 R/W RS-232 ( Modem ) Status
Revision History
Version 1.0 -- 20 May 1991 -- original release.
Warranty
The user of this software assumes all liability for its use. In no
case shall MarshallSoft be liable for any damages, including any
incidental or consequential damages.
Page 7
Using the Library
The first thing to do is to copy all the files from the PCL
distribution disk to a working disk, and put the original PCL
distribution disk in a safe place.
The PCL has been tested on a TANDY 1000 ( IBM PC clone ), a TANDY
3000 ( IBM AT clone ), a TANDY 1400LT ( IBM XT clone ), and a
Gateway 2000 Cache ( 25 MHZ 80386-DX ).
For an example of PCL use, examine the terminal emulator program
CALLPGM.PAS. The user should compile CALLPGM.PAS as a test of the
library.
If you have two computers, then you can connect them together with
a null modem cable and run CALLPGM on both machines. Whatever is
typed on one machine should appear on the other, and vice versa.
Depending on the design of the null modem cable, CALLPGM.PAS may
need to be modified so that it does not wait for DSR. This is
clearly documented in the CALLPGM.PAS code.
If you have a modem, then use CALLPGM to call up any bulletin
board system ( BBS ). There are many free BBSs around the
country. Look in any issue of "Computer Shopper" ( available in
bookstores, computer shops, and many grocery stores ) for a list
of current systems.
Page 8
Compiling
Registered users may wish to assemble PCL_LIB.ASM. Use the /MX
switch in order to disable automatic conversion from lower case to
to upper case. To assemble using the Microsoft assembler:
MASM PCL_LIB /MX;
To build the library TPU:
TPC PCL
To compile the sample program:
TPC CALLPGM
Page 9
Problems
If you cannot get your application to run properly, first compile
and run the terminal emulator program CALLPGM provided on your
distribution disk.
If CALLPGM runs correctly, then you have made a programming
mistake in your application. MarshallSoft cannot debug your
application, especially over the telephone! However, consider
each of the following when searching for an error in your
application.
1. Did you include the "uses PCL" statement ?
2. Is your receive buffer large enough ? If you are using 1K data
blocks in a file transfer protocol such as YMODEM, then your
receive buffer should be 1K or more.
3. Have you selected too high a baud rate ? Always start with
the slowest baud rate. If only one COM port is being run, you
should be able to run at 38400 baud.
4. Are you attempting to run another application in the
background ? Try running without any other programs running in
the background.
5. If you are running two COM ports simultaneously, are you using
seperate receive buffers ? ( you should ).
6. Did SioReset return a zero value ? If not, then you must call
SioReset again. See CALLPGM.PAS for an example.
If CALLPGM does not run, then either there is a physical
connection problem or your computer isn't as compatible as you
thought! Registered users can always call (205) 881 - 4630 after
5 PM CST Monday through Friday for help.
Page 10
Library Reference
The remainder of this manual list all the PCL functions. Every
library function will return a value as follows:
1. Negative values for error conditions. See last page of this
manual for a list of error values and their meanings.
2. Non-negative values when returning data ( eg: SioLine ).
3. Zero otherwise.
When debugging an application, be sure to test all return values.
Use SioError to print the associated text for errors.
/*** example code segment ***/
RetCode := SioFunction(); (* any PCL function *)
if RetCode < 0 then begin
RetCode := SioError(RetCode);
(* ...do some stuff... *)
end;
Page 11
SioBaud
Function
Sets the baud rate of the selected port.
Syntax
function SioBaud(Port,BaudCode : Integer) : Integer;
Arguments
Port : Port selected (COM1..COM4).
BaudCode : Baud code.
Remarks
The SioBaud function sets the baud rate without resetting the
port. It is used to change the baud rate after calling SioReset.
Baud Code Baud Rate PCL Name
0 300 Baud300
1 600 Baud600
2 1200 Baud1200
3 2400 Baud2400
4 4800 Baud4800
5 9600 Baud9600
6 19200 Baud19200
7 38400 Baud38400
8 57600 Baud57600
9 115200 Baud115200
Returns
-2 : Port not enabled. Must call SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
-11 : Bad baud rate code. See above code values.
Example
/* do auto baud detect */
for Code = 0 to 9 do begin
RetCode := SioBaud(Port,Code);
RetCode := SioPutc(Port,'A');
if SioGetc(Port,18) = Ord('A') then
writeln('Baud rate detected');
(*...do something here...*)
end
end;
Page 12
SioBrkKey
Function
Return non-zero if the Control-BREAK key was pressed.
Syntax
function SioBrkKey : Integer;
Remarks
The SioBrkKey function returns a TRUE value ( non-zero ) if the
Control-BREAK key was pressed, else it returns a zero. Use
SioBrkKey as a safety exit from a polling loop. Don't mix this
function up with SioBrkSig.
Returns
-1 : Control-BREAK was pressed.
0 : Control-BREAK was NOT pressed.
Example
while TRUE do begin
if SioBrkKey then begin
writeln('User typed Contrl-BREAK');
RetCode := SioDone(Port);
halt;
end;
(* do some other stuff *)
end;
Page 13
SioBrkSig
Function
Asserts, cancels, or detects BREAK signal.
Syntax
function SioBrkSig(Port : Integer; Cmd : Char) : Boolean;
Arguments
Port : Port selected (COM1,COM2,COM3,or COM4)
Cmd : ASSERT, CANCEL, or DETECT
Remarks
The SioBrkSig function controls the BREAK bit in the line status
register. The legal commands are:
ASSERT ('A') to assert BREAK
CANCEL ('C') to cancel BREAK
DETECT ('D') to detect BREAK
ASSERT, CANCEL, and DETECT are defined in PCL.PAS. See CALLPGM.PAS
for an example of the use of SioBrkSig.
Returns
-2 : Port not enabled. Must call SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
-6 : Illegal command. Expected 'A', 'C', or 'D'.
>0 : BREAK signal detected ( DETECT only )
Example
(* Assert BREAK for 1 second *)
RetCode := SioBrkSig(Port,ASSERT);
RetCode := SioDelay(18);
RetCode := SioBrkSig(Port,CANCEL);
(* Detect BREAK *)
if SioBrkSig(Port,DETECT) then begin
writeln('BREAK signal detected');
(* ...do some more stuff... *)
end
Page 14
SioCrtWrite
Function
Write character to the screen.
Syntax
function SioCrtWrite(ch : Char) : Integer;
Arguments
ch = Character to write
Remarks
The SioCrtWrite function uses the BIOS to write a single character
to the screen at the current cursor location.
SioCrtWrite is faster than a call to the Pascal library and
for this reason is included in PCL.
Returns
zero
Example
Ch := SioGetc(COM1,18);
if Ch <> -1 then begin
(* do some stuff *)
end
Page 15
SioDTR
Function
Set, clear, or read the Data Terminal Ready ( DTR ) bit.
Syntax
function SioDTR(Port,Cmd : Integer) : Integer;
Arguments
Port : Port selected (COM1,COM2,COM3,or COM4)
Cmd : DTR command ( SET, CLEAR, or READ )
Remarks
The SioDTR function controls the Data Terminal Ready ( DTR ) bit
in the modem control register. Commands ( defined in PCL.PAS )
are:
SET ('S') to set DTR ( ON )
CLEAR ('C') to clear DTR ( OFF )
READ ('R') to read DTR
Returns
-2 : Port not enabled. Must call RetCode := SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
-5 : Not one of 'S', 'C', or 'R'.
0 : DTR is OFF (READ Command).
>0 : DTR is ON (READ Command).
Example
(* turn DTR on for modem connected to COM4 *)
RetCode := SioDTR(COM4,SET);
Page 16
RetCode := SioDelay
Function
Delays one or more tics.
Syntax
function SioDelay(Tics : Integer) : Integer;
Arguments
Tics : Number of timer tics ( 18.2 per second )
Remarks
The SioDelay function is used to delay one or more timer tics,
where each timer tic is approximately 55 milliseconds ( 18 to the
second ). See SioTimer also.
Returns
zero
Example
RetCode := SioDelay(5*18); (* delay 5 seconds *)
Page 17
SioDone
Function
Terminates further serial processing.
Syntax
function SioDone(Port : Integer) : Integer;
Arguments
Port : Port selected (COM1,COM2,COM3,or COM4)
Remarks
The SioDone function terminates further serial processing.
SioDone MUST be called before exiting your application so that
interrupts can be restored to their original state. Failure to do
this can crash the operating system. If you forget to call
SioDone before exiting, be sure to re-boot your computer.
Returns
-2 : Port not enabled. Must call RetCode := SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
Example
(* terminate processing for COM3 *)
RetCode := SioDone(COM3);
Page 18
SioError
Function
Displays error in text.
Syntax
function SioError(Code : Integer) : Integer;
Arguments
Code : Error code returned from a PCL function
Remarks
The SioError function displays the error in text corresponding to
the error code. During development of a communications
application, it is a good idea to always test return codes, and
print out their descriptions with SioError.
Returns
none
Example
RetCode := SioReset(Port,Baud4800);
if RetCode < 0 then RetCode := SioError(RetCode);
Page 19
SioGetc
Function
Reads the next character from the serial line.
Syntax
function SioGetc(Port,Tics : Integer) : Integer;
Arguments
Port : COM1 to COM4
Tics : Number of timer tics
Remarks
The SioGetc function reads the selected serial port. The function
will wait for the number of system tics given by the 'Tics'
argument before returning 'timed out'. There are 18 tics to the
second.
To specify no waiting, call SioGetc with Tics = 0.
Returns
-2 : Port not enabled. Must call RetCode := SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
-1 : If timed out.
>0 : Character read.
Example
RetCode := SioGetc(COM1,1);
if RetCode <> -1 then writeln('Character is ', chr(RetCode) );
else writeln('Timed out');
Page 20
SioKeyPress
Function
Detects if keyboard has been pressed.
Syntax
function SioKeyPress() : Boolean;
Remarks
The SioKeyPress function uses the BIOS to test the keyboard for a
key press.
Returns
zero
Example
if SioKeyPress begin
(* ...do something... *)
end;
Page 21
SioKeyRead
Function
Reads the keyboard.
Syntax
function SioKeyRead : Integer;
Remarks
The SioKeyRead function uses the BIOS to read the keyboard. Will
wait until a character is typed.
SioKeyRead is faster than using the Pascal library.
Returns
character typed.
Example
if SioKeyPress then begin
RetCode := SioKeyRead();
end
Page 22
SioLine
Function
Reads the line status register.
Syntax
function SioLine(Port : Integer) : Integer;
Arguments
Port : Port selected (COM1,COM2,COM3,or COM4)
Remarks
The SioLine function reads the line status register. The
individual bit masks are as follows:
$20 = Transmitter Buffer Empty.
$10 = Break detected.
$08 = Framming error.
$04 = Parity error.
$02 = Overrun error.
$01 = Data ready.
The above are documented in the file PCL.PAS.
Returns
-2 : Port not enabled. Must call RetCode := SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
>0 : Line status ( rightmost byte of word ).
Example
RetCode := SioLine(Port);
if(RetCode and (FramingError or ParityError or OverrunError)) <> 0
then
begin
if (RetCode and FramingError) <> 0 then writeln('Framing Error');
if (RetCode and ParityError) <> 0 then writeln('Parity Error');
if (RetCode and OverrunError) <> 0 then writeln('Overrun Error')
end
else writeln('No error');
Page 23
SioModem
Function
Reads the modem status register.
Syntax
function SioModem(Port : Integer; Mask : Char) ; Integer;
Arguments
Port : Port selected (COM1,COM2,COM3,or COM4)
Mask : Modem function mask
Remarks
The SioModem function reads the modem register. The bit
definitions for the function mask are as follows:
Bit PCL.PAS Name Function
7 DCD Data Carrier Detect
6 RI Ring Indicator
5 DSR Data Set Ready
4 CTS Clear To Send
3 DeltaDCD Delta DCD ( DCD has changed )
2 DeltaRI Delta RI ( RI has changed )
1 DeltaDSR Delta DSR ( DSR has changed )
0 DeltaCTS Delta CTS ( CTS has changed )
Bits 4 through 7 represent the absolute state of their respective
RS-232 inputs. Bits 0 through 3 repesent a change in the state of
their respective RS-232 inputs since last read.
The above definitions are also in the PCL.PAS file for use by your
application program.
Returns
-2 : Port not enabled. Must call RetCode := SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
>0 : Modem status ( rightmost byte of word ).
Example
(* any change in DCD ? *)
Status := SioModem(Port,DeltaDCD);
if Status < 0 then
begin
RetCode := SioError(Status);
Halt;
end;
else writeln('DCD status = ', SioModem(Port,DCD) );
Page 24
SioParms
Function
Sets parity, stop bits, and word length.
Syntax
function SioParms(Port,ParityCode,StopBitsCode,WordLengthCode: Integer)
: Integer;
Arguments
Port : Port selected (COM1,COM2,COM3,or COM4)
ParityCode : Parity code [0,1,2]
StopBitsCode : Stop bits code [0,1]
WordLengthCode : Word length code [0,1,2,3]
Remarks
The SioParms function sets the parity, stop bits, and word length.
If the default parity ( none ), stop bits ( 1 ), or word length (
8 ) is not acceptable, then they can be changed by calling
SioParms. SioParms can be called either before or after calling
SioReset. See file PCL.PAS.
Value Description PCL.PAS Name
ParityCode: *0 no parity NoParity
1 odd parity OddParity
2 even parity EvenParity
StopBitsCode: *0 1 stop bit OneStopBit
1 2 stop bits TwoStopBits
WordLengthCode: 0 5 data bits WordLength5
1 6 data bits WordLength6
2 7 data bits WordLength7
*3 8 data bits WordLength8
* = Default
Returns
-2 : Port not enabled. Must call RetCode := SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
-7 : Bad parity code selected. Value must be 0 to 2.
-8 : Bad stop bits code. Value must be 0 or 1.
-9 : Bad word length code. Value must be 0 to 3.
Example
RetCode := SioParms(COM1,NoParity,OneStopBit,WordLength8);
Page 25
SioPutc
Function
Transmit a character over a serial line.
Syntax
function SioPutc(Port : Integer; Ch : Char) : Integer;
Arguments
Port : Port selected (COM1,COM2,COM3,or COM4)
Ch : Character to send
Remarks
The SioPutc function transmits one character over the selected
serial line.
Returns
-2 : Port not enabled. Must call RetCode := SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
Example
crc := 0;
for i = 0 to 127 do begin
crc := crcupdate( buffer[i], crc);
RetCode := SioPutc(Port, buffer[i]);
end;
RetCode := SioPutc(crc);
Page 26
SioRTS
Function
Sets, clears, or reads the Request to Send ( RTS ) line.
Syntax
function SioRTS(Port : Integer; Cmd : Char) : Integer;
Arguments
Port : COM1 to COM4
Cmd : RTS command ( SET, CLEAR, or READ )
Remarks
The SioRTS function controls the Request to Send ( RTS ) bit in
the modem control register. Commands ( defined in PCL.PAS ) are:
SET ('S') set RTS ( ON )
CLEAR ('C') clear RTS ( OFF )
READ ('R') read RTS
Returns
-2 : Port not enabled. Must call RetCode := SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
-5 : Command is not one of 'S', 'C', or 'R'.
0 : RTS is OFF (READ Command).
>0 : RTS is ON (READ Command).
Example
(* turn off RTS for modem *)
RetCode := SioRTS(Port,CLEAR);
Page 27
SioReset
Function
Initialize a serial port for processing.
Syntax
function SioReset(Port,BaudCode : Integer) : Integer;
Arguments
Port : Port selected (COM1,COM2,COM3,or COM4)
BaudCode : baud code
Remarks
The SioReset function initializes the selected serial port.
SioReset should be called after calling SioParm and SioRxBuf but
before making any other calls to PCL. SioReset uses the parity,
stop bits, and word length value previously set if SioParm was
called, otherwise the default values ( see SioParm ) are used.
Recall that COM1 and COM3 share the same interrupt vector and
therefore cannot operate simultaneously. Similiarly, COM2 and
COM4 cannot operate simultaneously. Any other combination of two
ports can be used.
See SioBaud for a list of the baud rate codes, or see "PCL.PAS".
Returns
-4 : Bad port selected. Value must be 0 to 3.
-11 : Bad baud rate code selected. Value must be 0 to 9.
Example
RetCode := SioRxBuf(COM1,Buffer,Size128);
RetCode := SioReset(Com1,Baud38400);
if RetCode = 0 then writeln('RESET ok');
else begin
RetCode := SioError(rc);
if (RetCode and OverrunError) <> 0 then writeln('Overrun Error');
if (RetCode and ParityError) <> 0 then writeln('Parity Error');
if (RetCode and FramingError) <> 0 then writeln('Framing Error');
if (RetCode and BreakDetected) <> 0 then writeln('Break Detected');
end;
Page 28
SioRxBuf
Function
Sets up receive buffers.
Syntax
function SioRxBuf(Port,BufferOfs,BufferSeg,SizeCode : Integer) : Integer;
Arguments
Port : Port selected (COM1,COM2,COM3,or COM4)
Buffer : Receive buffer
SizeCode : Buffer size code
Remarks
The SioRxBuf function passes the address and size of the receive
buffer to PCL. Recall that PCL requires a receive buffer for each
port in simultaneous operation since the receive function is
interrupt driven. SioRxBuf passes the receive buffer to PCL for
both the primary ( COM1/COM3 ) and secondary ( COM2/COM4 ) ports.
It must be called before any incoming characters can be received.
SioRxBuf should be called before SioReset. Buffer size codes are
listed in "PCL.PAS".
Size Code Buffer Size PCL.PAS Name
0 8 bytes Size8
1 16 bytes Size16
2 32 bytes Size32
3 64 bytes Size64
4 128 bytes Size128
5 256 bytes Size256
6 512 bytes Size512
7 1024 bytes Size1024
8 2048 bytes Size2048
9 4096 bytes Size4096
10 8192 bytes Size8192
11 16384 bytes Size16384
Returns
-2 : Port not enabled. Must call RetCode := SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
-10 : Bad buffer size code. Value must be between 0 and 11.
Example
RetCode := SioRxBuf( COM1, RxBuf, 128);
Page 29
SioRxFlush
Function
To flush the receive buffer associated with the specified port.
Syntax
function SioRxFlush(Port: Integer) : Integer;
Arguments
Port : Port selected (COM1,COM2,COM3,or COM4)
Remarks
The SioRxFlush function will delete any characters in the receive
buffer for the specified port. After execution, the receive
buffer will be empty. Call SioRxBuf after resetting a port in
order to delete any spurious characters.
Returns
-2 : Port not enabled. Must call RetCode := SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
Example
(* setup receive buffer and reset port *)
RetCode := SioRxBuf(COM1,buffer,Size1024);
RetCode := SioReset(COM1,Baud115200);
(* flush any spurious character *)
RetCode := SioRxFlush(COM1);
(* ready for serial processing ! *)
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SioRxQue
Function
Returns the number of characters in the receive queue.
Syntax
function SioRxQue(Port : Integer) : Integer;
Arguments
Port : Port selected (COM1,COM2,COM3,or COM4)
Remarks
The SioRxQue function will return the number of characters in the
receive queue. It can be used to implement XON/XOFF flow control.
Returns
-2 : Port not enabled. Must call RetCode := SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
Example
RetCode := SioRxBuf(COM1,Buffer,Size128);
(* implement XON / XOFF *)
count := SioRxQue(COM1);
if (last=XON) and (count>120) then
begin
RetCode := SioPutc(COM1,char(XOFF));
last := XOFF;
end
if (last=XOFF) and (count<8) then
begin
RetCode := SioPutc(COM1,char(XON));
last := XON;
end
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SioTimer
Function
Returns the number of system clock tics since midnight.
Syntax
function SioTimer : Integer;
Remarks
The SioTimer function will return the number of system clock tics
since midnight, at 18.2065 tics per second. This function is
usefull for timeing various functions. Also see SioDelay.
Returns
timer tics
Example
Time := SioTimer();
(* do some stuff *)
writeln('Elasped time ', SioTimer - Time );
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SioUnGetc
Function
"Un-gets" the last character read with SioGetc.
Syntax
function SioUnGetc(Port : Integer; Ch : Char) : Integer;
Arguments
Port : Port selected (COM1,COM2,COM3,or COM4)
Ch : Character to unget
Remarks
The SioUnGetc function returns ( pushes ) the character back into
the serial input buffer. The character pushed will be the next
character returned by SioGetc. Only one character can be pushed
back. This function works just like the "ungetc" function in the C
language.
Returns
-2 : Port not enabled. Must call RetCode := SioReset first.
-4 : Bad port selected. Value must be 0 to 3.
Example
RetCode := SioUnGetc(Port,c);
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Function Sumary
+-------------+----------+----------+----------+----------+
| Function | Arg1 | Arg2 | Arg3 | Arg4 |
+-------------+----------+----------+----------+----------+
| SioBaud | Port | BaudCode | | |
+-------------+----------+----------+----------+----------+
| SioBrkKey | | | | |
+-------------+----------+----------+----------+----------+
| SioBrkSig | Port | Cmd | | |
+-------------+----------+----------+----------+----------+
| SioCrtWrite| Ch | | | |
+-------------+----------+----------+----------+----------+
| SioDTR | Port | Cmd | | |
+-------------+----------+----------+----------+----------+
| SioDelay | Tics | | | |
+-------------+----------+----------+----------+----------+
| SioDone | Port | | | |
+-------------+----------+----------+----------+----------+
| SioError | Code | | | |
+-------------+----------+----------+----------+----------+
| SioGetc | Port | Tics | | |
+-------------+----------+----------+----------+----------+
| SioKeyPress| | | | |
+-------------+----------+----------+----------+----------+
| SioKeyRead | | | | |
+-------------+----------+----------+----------+----------+
| SioLine | Port | | | |
+-------------+----------+----------+----------+----------+
| SioModem | Port | Mask | | |
+-------------+----------+----------+----------+----------+
| SioParms | Port | Parity | StopBits |WordLength|
+-------------+----------+----------+----------+----------+
| SioPutc | Port | Ch | | |
+-------------+----------+----------+----------+----------+
| SioRTS | Port | Cmd | | |
+-------------+----------+----------+----------+----------+
| SioReset | Port | BaudCode | | |
+-------------+----------+----------+----------+----------+
| SioRxBuf | Port | Buffer | SizeCode | |
+-------------+----------+----------+----------+----------+
| SioRxFlush | Port | | | |
+-------------+----------+----------+----------+----------+
| SioRxQue | Port | | | |
+-------------+----------+----------+----------+----------+
| SioTimer | | | | |
+-------------+----------+----------+----------+----------+
| SioUnGetc | Port | Ch | | |
+-------------+----------+----------+----------+----------+
Page 34
Error Code Summary
Code Description
0 No error.
-1 Timeout waiting for input. Only returned by SioGetc.
-2 Port not enabled. Must call SioReset first.
-3 No buffer available. Must call SioRxBuf before
calling SioReset.
-4 Bad port specified. Must be 0 to 3. Recall that COM1
is port 0, COM2 is port 1, etc.
-5 Expected 'S', 'C', or 'R' as second argument.
-6 Expected 'A', 'C', or 'D' as second argument.
-7 Bad parity code specified. Must be 0 to 7.
-8 Bad stop bits code specified. Must be 0 or 1.
-9 Bad wordlength code specified. Must be 0 to 3.
-10 Bad buffer size code specified. Must be 0 to 11.
-11 Bad baud rate code. Must be 0 to 9.
Page 35
