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Personal Communications Library
For Turbo Pascal 4.0 & up
( PCL4P )
REFERENCE MANUAL
Version 3.0
Jan 15, 1992
This software is provided as-is.
There are no warranties, expressed or implied.
Copyright (C) 1992
All rights reserved
MarshallSoft Computing, Inc.
Post Office Box 4543
Huntsville AL 35815
Phone (205) 881-4630
PCL4P Reference Manual Page 1
Table of Contents
Chapter Page
Table of Contents.............................2
Introduction..................................3
SioBaud.......................................4
SioBrkKey.....................................5
SioBrkSig.....................................6
SioCTS........................................7
SioDCD........................................8
SioDelay......................................9
SioDone......................................10
SioDSR.......................................11
SioDTR.......................................12
SioError.....................................13
SioGetc......................................14
SioLine......................................15
SioLoopBack..................................16
SioModem.....................................17
SioParms.....................................18
SioPutc......................................19
SioReset.....................................20
SioRI........................................21
SioRTS.......................................22
SioRxBuf.....................................23
SioRxFlush...................................24
SioRxQue.....................................25
SioTimer.....................................26
SioUART......................................27
SioUnGetc....................................28
Function Summary................................29
Error Code Summary..............................30
PCL4P Reference Manual Page 2
Introduction
This manual list all the PCL4P functions in alphabetical order.
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 PCL4P function *) |
| if RetCode < 0 then begin |
| RetCode := SioError(RetCode); |
| (* ...do some stuff... *) |
| end; |
+--------------------------------------------------------+
For more examples, examine each of the example programs provided.
Also look at the examples associated with each library function
described in the following section.
PCL4P Reference Manual Page 3
SioBaud
Function Sets the baud rate of the selected port.
Syntax function SioBaud(Port,BaudCode:Integer) : Integer;
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 PCL4P.H 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 -4 : Port out of range. Expecting 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
begin
writeln('Baud rate detected');
(*...do something here...*)
end
end;
See Also SioReset
PCL4P Reference Manual Page 4
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
if SioBrkKey then
begin
writeln('User typed Contrl-BREAK');
RetCode := SioDone(Port);
halt;
end;
See Also SioBrkSig
PCL4P Reference Manual Page 5
SioBrkSig
Function Asserts, cancels, or detects BREAK signal.
Syntax function SioBrkSig(Port:Integer;Cmd:Char) : Boolean;
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 PCL4P.H.
See TERM.C for an example of the use of SioBrkSig.
Returns -2 : Port not enabled. Call SioReset first.
-4 : Port out of range. Expecting 0 to 3.
-6 : Illegal command. Expected 'A', 'C', or 'D'.
>0 : BREAK signal detected ( DETECT command 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
See Also SioBrkKey
PCL4P Reference Manual Page 6
SioCTS
Function Reads the Clear to Send ( CTS ) modem status bit.
Syntax function SioCTS(Port:Integer) : Integer;
Remarks The SioCTS function is used to read the Clear to Send (
CTS ) modem status bit.
Returns -2 : Port not enabled. Call SioReset first.
-4 : Port out of range. Expecting 0 to 3.
0 : CTS is clear.
>0 : CTS is set.
Example
RetCode := SioCTS(Port);
if RetCode > 0 then write('CTS is set');
else write('CTS is clear');
See Also SioDSR, SioRI, SioDCD, and SioModem.
PCL4P Reference Manual Page 7
SioDCD
Function Reads the Data Carrier Detect ( DCD ) modem status bit.
Syntax function SioDCD(Port:Integer) : Integer;
Remarks The SioDCD function is used to read the Data Carrier
Detect ( DCD ) modem status bit. Also see SioModem.
Returns -2 : Port not enabled. Call SioReset first.
-4 : Port out of range. Expecting 0 to 3.
0 : DCD is clear.
>0 : DCD is set.
Example
RetCode := SioDCD(Port);
if RetCode > 0 then write('DCD is set');
else write('DCD is clear');
See Also SioDSR, SioCTS, SioRI, and SioModem.
PCL4P Reference Manual Page 8
SioDelay
Function Delays one or more tics.
Syntax function SioDelay(Tics:Integer) : Integer;
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 ).
Returns zero
Example (* delay 5 seconds *)
RetCode := SioDelay(5*18);
See Also SioTimer
PCL4P Reference Manual Page 9
SioDone
Function Terminates further serial processing.
Syntax function SioDone(Port:Integer) : Integer
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. You
can call SioDone even if SioReset has not been called,
so it is good practice to always call SioDone before
exiting your application.
Returns -2 : Port not enabled. Call SioReset first.
-4 : Port out of range. Expecting 0 to 3.
Example (* terminate processing for COM3 *)
RetCode := SioDone(COM3);
See Also SioReset.
PCL4P Reference Manual Page 10
SioDSR
Function Reads the Data Set Ready ( DSR ) modem status bit.
Syntax function SioDSR(Port:Integer) : Integer;
Remarks The SioDSR function is used to read the Data Set
Ready ( DSR ) modem status bit.
Returns -2 : Port not enabled. Call SioReset first.
-4 : Port out of range. Expecting 0 to 3.
0 : DSR is clear.
>0 : DSR is set
Example
RetCode := SioDSR(Port);
if RetCode > 0 then write('DSR is set');
else write('DSR is clear');
See Also SioCTS, SioRI, SioDCD, and SioModem
PCL4P Reference Manual Page 11
SioDTR
Function Set, clear, or read the Data Terminal Ready ( DTR ) bit.
Syntax function SioDTR(Port,Cmd:Integer) : Integer;
Remarks The SioDTR function controls the Data Terminal Ready (
DTR ) bit in the modem control register. Commands (
defined in PCL4P.H ) are:
SET ('S') to set DTR ( ON )
CLEAR ('C') to clear DTR ( OFF )
READ ('R') to read DTR
Returns -2 : Port not enabled. Call SioReset first.
-4 : Port out of range. Expecting 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);
See Also SioRTS.
PCL4P Reference Manual Page 12
SioError
Function Displays error in text.
Syntax function SioError(Code:Integer) : Integer;
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 zero
Example
RetCode := SioReset(Port,Baud4800);
if RetCode < 0 then RetCode := SioError(RetCode);
PCL4P Reference Manual Page 13
SioGetc
Function Reads the next character from the serial line.
Syntax function SioGetc(Port,Tics:Integer) : Integer;
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. Call SioReset first.
-4 : Port out of range. Expecting 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');
See Also SioUnGetc and SioPutc.
PCL4P Reference Manual Page 14
SioLine
Function Reads the line status register.
Syntax function SioLine(Port:Integer) : Integer;
Remarks The SioLine function reads the line status register.
The individual bit masks are as follows:
0x20 = Transmitter Buffer Empty.
0x10 = Break detected.
0x08 = Framming error.
0x04 = Parity error.
0x02 = Overrun error.
0x01 = Data ready.
The above are documented in the file PCL4P.H.
Returns -2 : Port not enabled. Call SioReset first.
-4 : Port out of range. Expecting 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');
See Also SioModem.
PCL4P Reference Manual Page 15
SioLoopBack
Function Does a UART loopback test.
Syntax function SioLoopBack(Port:Integer) : Integer;
Remarks SioLoopBack makes use of the built in loopback test
capability of the INS8250 UART. Normally SioLoopBack
will never need to be called except if you suspect
that your UART is bad. See the LOOPBACK.C program.
Returns 0 : Loopback test is successfull.
-2 : Port not enabled. Call SioReset first.
-4 : Port out of range. Expecting 0 to 3.
-12 : Loopback test fails.
Example
RetCode := SioLoopBack(Port);
if RetCode = 0
then write('Loopback test has succeeded');
else write('Loopback test has failed');
PCL4P Reference Manual Page 16
SioModem
Function Reads the modem status register.
Syntax function SioModem(Port:Integer; Mask:Char) ; Integer;
Remarks The SioModem function reads the modem register. The
bit definitions for the function mask are as follows:
Bit PCL4P.H 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 PCL4P.H file
for use by your application program.
Returns -2 : Port not enabled. Call SioReset first.
-4 : Port out of range. Expecting 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) );
See Also SioCTS, SioDCD, SioDSR and SioRI.
PCL4P Reference Manual Page 17
SioParms
Function Sets parity, stop bits, and word length.
Syntax function SioParms(Port,ParityCode,StopBitsCode,
WordLengthCode:Integer) : Integer;
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 PCL4P.H.
Value Description PCL4P.H Name
ParityCode: *0 no parity NoParity
1 odd parity OddParity
3 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 -4 : Port out of range. Expecting 0 to 3.
-7 : Bad parity code selected. Expecting 0 to 2.
-8 : Bad stop bits code. Expecting 0 or 1.
-9 : Bad word length code. Expecting 0 to 3.
Example
RetCode := SioParms(COM1,NoParity,OneStopBit,WordLength8);
See Also SioReset.
PCL4P Reference Manual Page 18
SioPutc
Function Transmit a character over a serial line.
Syntax function SioPutc(Port:Integer; Ch:Char) : Integer;
Remarks The SioPutc function transmits one character over the
selected serial line.
Returns -2 : Port not enabled. Call SioReset first.
-4 : Port out of range. Expecting 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);
See Also SioGetc.
PCL4P Reference Manual Page 19
SioReset
Function Initialize a serial port for processing.
Syntax function SioReset(Port,BaudCode:Integer) : Integer;
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
PCL4P. 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.
By specifing NORESET ( -1 ) for the baud rate code,
the port will NOT be reset. This is used to "take
over" a port from a host communications program that
allows a "DOS gateway". External protocols can be
implemented this way. See SioBaud for a list of the
baud rate codes, or see "PCL4P.H".
Returns -3 : No buffer available. Call SioRxBuf first.
-4 : Port out of range. Expecting 0 to 3.
-11 : Bad baud rate code selected. Expecting 0 to 9.
-13 : UART undefined. SioUART(Port,0) was called
previously.
-14 : Bad or missing UART. You may not have hardware
present.
-15 : Port already enabled. SioReset has already been
called.
-16 : Cannot enable both COM1 & COM3 or COM2 & COM4.
Example
RetCode := SioRxBuf(COM1,Ofs(Buffer),Seg(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;
See Also SioBaud, SioParms, SioRxBuf, SioDone, and SioUART.
PCL4P Reference Manual Page 20
SioRI
Function Reads the Ring Indicator ( RI ) modem status bit.
Syntax function SioRI(Port:Integer) : Integer;
Remarks The SioRI function is used to read the Ring Indicator
( RI ) modem status bit. Also see SioModem.
Returns -2 : Port not enabled. Call SioReset first.
-4 : Port out of range. Expecting 0 to 3.
0 : RI is clear.
>0 : RI is set ( RING has occurred ).
Example
RetCode := SioRI(Port);
if RetCode > 0 then write('RING');
See Also SioDSR, SioCTS, SioDCD, and SioModem.
PCL4P Reference Manual Page 21
SioRTS
Function Sets, clears, or reads the Request to Send ( RTS )
line.
Syntax function SioRTS(Port:Integer; Cmd:Char) : Integer;
Remarks The SioRTS function controls the Request to Send (
RTS ) bit in the modem control register. Commands (
defined in PCL4P.H ) are:
SET ('S') -- set RTS ( ON )
CLEAR ('C') -- clear RTS ( OFF )
READ ('R') -- read RTS
Returns -2 : Port not enabled. Call SioReset first.
-4 : Port out of range. Expecting 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);
See Also SioDTR.
PCL4P Reference Manual Page 22
SioRxBuf
Function Sets up receive buffers.
Syntax function SioRxBuf(Port,BufferOfs,BufferSeg,
SizeCode:Integer) : Integer;
Remarks The SioRxBuf function passes the address and size of
the receive buffer to PCL4P. Recall that PCL4P
requires a receive buffer for each port in
simultaneous operation since the receive function is
interrupt driven. SioRxBuf passes the receive buffer
to PCL4P for both the primary ( COM1/COM3 ) and
secondary ( COM2/COM4 ) ports. It must be called
before any incoming characters can be received.
SioRxBuf must be called before SioReset. Buffer size
codes are listed in "PCL4P.H".
Size Code Buffer Size PCL4P.H 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 -4 : Port out of range. Expecting 0 to 3.
-10 : Bad buffer size code. Expecting 0 to 11.
Example
RetCode := SioRxBuf( COM1, Ofs(RxBuf),Seg(RxBuf), 128);
See Also SioReset.
PCL4P Reference Manual Page 23
SioRxFlush
Function To flush the receive buffer associated with the
specified port.
Syntax function SioRxFlush(Port:Integer) : Integer;
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. Call SioReset first.
-4 : Port out of range. Expecting 0 to 3.
Example
(* setup receive buffer and reset port *)
RetCode := SioRxBuf(COM1,Ofs(Buffer),Seg(Buffer),Size1024);
RetCode := SioReset(COM1,Baud115200);
(* flush any spurious character *)
RetCode := SioRxFlush(COM1);
(* ready for serial processing ! *)
See Also SioRxQue.
PCL4P Reference Manual Page 24
SioRxQue
Function Returns the number of characters in the receive queue.
Syntax function SioRxQue(Port:Integer) : Integer;
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. Call SioReset first.
-4 : Port out of range. Expecting 0 to 3.
Example
RetCode := SioRxBuf(COM1,Ofs(Buffer),Seg(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
See Also SioRxFlush.
PCL4P Reference Manual Page 25
SioTimer
Function Returns the number of system clock tics since midnight.
Syntax function SioTimer : LongInt;
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 timing various functions.
Also see SioDelay.
Returns timer tics.
Example
Var Time : LongInt;
...
Time := SioTimer();
(* do some stuff *)
Writeln('Elasped time ', SioTimer - Time );
See Also SioDelay.
PCL4P Reference Manual Page 26
SioUART
Function Sets the UART base address.
Syntax function SioUART(Port,Address:Integer) : Integer;
Remarks The SioUART function sets the UART base address for
the specified port. SioUART must be called before
SioReset in order to have effect. Be extremely sure
that you know what you are doing! Note that PCL4P uses
the standard PC/XT/AT port addresses, interrupt
request lines, and interrupt service vectors.
Therefore, this function is only needed for
non-standard ports.
Returns >0 : The previous base address for this port.
-4 : Port out of range. Expecting 0 to 3.
Example (* Record fact that you don't have COM4 *)
RetCode := SioUART(COM4, 0);
See Also SioReset.
PCL4P Reference Manual Page 27
SioUnGetc
Function "Un-gets" the last character read with SioGetc().
Syntax function SioUnGetc(Port:Integer; Ch:Char) : Integer;
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. Call SioReset first.
-4 : Port out of range. Expecting 0 to 3.
Example (* push back c so next SioGetc will get it *)
RetCode := SioUnGetc(Port,c);
See Also SioReset.
PCL4P Reference Manual Page 28
Function Sumary
+-------------+----------+----------+----------+----------+
| Function | Arg1 | Arg2 | Arg3 | Arg4 |
+=============+==========+==========+==========+==========+
| SioBaud | Port | BaudCode | | |
| SioBrkKey | | | | |
| SioBrkSig | Port | Cmd | | |
| SioCTS | Port | | | |
| SioDCD | Port | | | |
| SioDelay | Tics | | | |
| SioDone | Port | | | |
| SioDSR | Port | | | |
| SioDTR | Port | Cmd | | |
| SioError | Code | | | |
| SioGetc | Port | Tics | | |
| SioLine | Port | | | |
| SioLoopBack | Port | | | |
| SioParms | Port | Parity | StopBits |WordLength|
| SioPutc | Port | Ch | | |
| SioReset | Port | BaudCode | | |
| SioRI | Port | | | |
| SioRTS | Port | Cmd | | |
| SioRxBuf | Port | Ofs(Buff)| Seg(Buff)| SizeCode |
| SioRxFlush | Port | | | |
| SioRxQue | Port | | | |
| SioTimer | | | | |
| SioUART | Port | Address | | |
| SioUnGetc | Port | Ch | | |
+-------------+----------+----------+----------+----------+
( 26 functions )
PCL4P Reference Manual Page 29
Error Code Summary
Code Description
0 No error.
-1 Timeout waiting for input. (Only returned by SioGetc).
-2 Port not enabled. Call SioReset first.
-3 No buffer available. Call SioRxBuf before calling
SioReset.
-4 Port out of range. Expecting 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.
-12 Loopback test fails.
-13 UART undefined.
-14 Missing or bad UART.
-15 Port already enabled.
-16 Cannot enable both COM1 and COM3 or COM2 and COM4.
PCL4P Reference Manual Page 30
