分析BACnet协议栈1Word格式.docx
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*/
/*Useionicewrappertoimproveserialperformance:
$sudoionice-c1-n0./bin/bacserv12345
*/
/*handlereturnedfromopen（）*/
staticintRS485_Handle=-1;
/*baudratesettingsaredefinedin<
asm/termbits.h>
whichis
includedby<
staticunsignedintRS485_Baud=B38400;
//波特率选择38400bps
/*serialportname,/dev/ttyS0,
/dev/ttyUSB0forUSB->
RS485fromB&
BElectronicsUSOPTL4*/
staticchar*RS485_Port_Name="
/dev/ttyUSB0"
;
/*系统默认是通过USB转485的，根据需要设置，若你的开发板用485接口，则用staticchar*RS485_Port_Name="
/dev/ttyS0"
代替*/
/*someterminalI/OhaveRS-485specificfunctionality*/
#ifndefRS485MOD
#defineRS485MOD0
#endif
/*serialI/Osettings*/
staticstructtermiosRS485_oldtio;
/*Ringbufferforincomingbytes,inordertospeedupthereceiving.*/
staticFIFO_BUFFERRx_FIFO;
/*buffersizeneedstobeapowerof2*/
staticuint8_tRx_Buffer[4096];
#define_POSIX_SOURCE1/*POSIXcompliantsource*/
/*********************************************************************
*DESCRIPTION:
Configurestheinterfacename
*RETURN:
none
*ALGORITHM:
*NOTES:
*********************************************************************/
voidRS485_Set_Interface（
char*ifname）
{
/*note:
expectsaconstantchar,orcharfromtheheap*/
if（ifname）{
RS485_Port_Name=ifname;
}
}
Returnstheinterfacename
constchar*RS485_Interface（
void）
returnRS485_Port_Name;
/****************************************************************************
Returnsthebaudratethatwearecurrentlyrunningat
*****************************************************************************/
uint32_tRS485_Get_Baud_Rate（
uint32_tbaud=0;
switch（RS485_Baud）{
caseB0:
baud=0;
break;
caseB50:
baud=50;
caseB75:
baud=75;
caseB110:
baud=110;
caseB134:
baud=134;
caseB150:
baud=150;
caseB200:
baud=200;
caseB300:
baud=300;
caseB600:
baud=600;
caseB1200:
baud=1200;
caseB1800:
baud=1800;
caseB2400:
baud=2400;
caseB4800:
baud=4800;
caseB9600:
baud=9600;
caseB19200:
baud=19200;
caseB38400:
baud=38400;
caseB57600:
baud=57600;
caseB115200:
baud=115200;
caseB230400:
baud=230400;
default:
baud=9600;
returnbaud;
SetsthebaudrateforthechipUSART
boolRS485_Set_Baud_Rate（
uint32_tbaud）
boolvalid=true;
switch（baud）{
case0:
RS485_Baud=B0;
case50:
RS485_Baud=B50;
case75:
RS485_Baud=B75;
case110:
RS485_Baud=B110;
case134:
RS485_Baud=B134;
case150:
RS485_Baud=B150;
case200:
RS485_Baud=B200;
break;
case300:
RS485_Baud=B300;
case600:
RS485_Baud=B600;
case1200:
RS485_Baud=B1200;
case1800:
RS485_Baud=B1800;
case2400:
RS485_Baud=B2400;
case4800:
RS485_Baud=B4800;
case9600:
RS485_Baud=B9600;
case19200:
RS485_Baud=B19200;
case38400:
RS485_Baud=B38400;
case57600:
RS485_Baud=B57600;
case115200:
RS485_Baud=B115200;
case230400:
RS485_Baud=B230400;
valid=false;
if（valid）{
/*FIXME:
storethebaudrate*/
returnvalid;
Transmitaframeonthewire
voidRS485_Send_Frame（
volatilestructmstp_port_struct_t*mstp_port,
/*portspecificdata*/
uint8_t*buffer,
/*frametosend（upto501bytesofdata）*/
uint16_tnbytes）
{
/*numberofbytesofdata（upto501）*/
uint32_tturnaround_time=Tturnaround*1000;
uint32_tbaud=RS485_Get_Baud_Rate（）;
ssize_twritten=0;
intgreska;
/*sleepingforturnaroundtimeisnecessarytogiveotherdevices
timetochangefromsendingtoreceivingstate.*/
usleep（turnaround_time/baud）;
//至少要等待Tturnaround时间才启动RS485缓冲器发送
/*
On
success,
the
numberofbyteswrittenarereturned（zeroindicates
nothingwaswritten）.
Onerror,-1
is
returned,
and
errno
set
appropriately.
If
count
iszeroandthefiledescriptorreferstoa
regularfile,0willbereturnedwithoutcausinganyothereffect.
For
aspecialfile,theresultsarenotportable.
written=write（RS485_Handle,buffer,nbytes）;
//RS485_Handle初始时是为-1，当发出open操作时应该是个正整数，而write函数的原型是（fd,buf,n）
greska=errno;
if（written<
=0）{
printf（"
writeerror:
%s\n"
strerror（greska））;
}else{
/*waituntilalloutputhasbeentransmitted.*/
tcdrain（RS485_Handle）;
//Linux中的传输等待函数
/*
/*perMSTPspec,sortof*/
if（mstp_port）{
mstp_port->
SilenceTimerReset（）;
return;
Getabyteofreceivedata
RS485_Check_UART_Data函数分别检查ReceiveError、DataAvailable。
然后选择端口从UART中读数据
voidRS485_Check_UART_Data（
volatilestructmstp_port_struct_t*mstp_port）
fd_setinput;
structtimevalwaiter;
uint8_tbuf[2048];
intn;
if（mstp_port->
ReceiveError==true）{
/*donothingbutwaitforstatemachinetocleartheerror*/
/*burningtime,sowaitalongertime*/
waiter.tv_sec=0;
waiter.tv_usec=5000;
}elseif（mstp_port->
DataAvailable==false）{
/*waitforstatemachinetoreadfromtheDataRegister*/
if（FIFO_Count（&
Rx_FIFO）>
0）{
/*dataisavailable*/
DataRegister=FIFO_Get（&
Rx_FIFO）;
DataAvailable=true;
/*FIFOisgivingdata-don'
twaitverylong*/
waiter.tv_usec=10;
/*FIFOisempty-waitalongertime*/
/*grabbytesandstuffthemintotheFIFOeverytime*/
FD_ZERO（&
input）;
FD_SET（RS485_Handle,&
n=select（RS485_Handle+1,&
input,NULL,NULL,&
waiter）;
if（n<
if（FD_ISSET（RS485_Handle,&
input））{
n=read（RS485_Handle,buf,sizeof（buf））;
FIFO_Add（&
Rx_FIFO,&
buf[0],n）;
voidRS485_Cleanup（
/*restoretheoldportsettings*/
tcsetattr（RS485_Handle,TCSANOW,&
RS485_oldtio）;
//tcgetattr用于获取终端的相关参数，而tcsetattr函数用于设置终端参数
close（RS485_Handle）;
voidRS485_Initialize（
structtermiosnewtio;
RS485:
Initializing%s"
RS485_Port_Name）;
Opendeviceforreadingandwriting.
Blockingmode-moreCPUef
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