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  EMBEDDED APPLICATIONS FCT 

 
 
 
 

2  Using the Embedded Application TCP/IP 
Functions for Data Exchange 

2.1  

Overview 

of 

Embedded Applications TCP/IP 

The TCP/IP features provided by the embedded 
application functions of the radio device are intended to 
provide a subset of the features normally available at the 
socket level when using a conventional TCP/IP stack, with 
some simplification and customization based on the 
specific features of the radio device. 

The features allow the application-writer to create and 
destroy UDP and TCP sockets, to control underlying 
GPRS PDP contexts, to transfer data to and from the radio 
device, and to interrogate IP status information about the 
active link. 

The socket interface is provided by a series of functions 
outlined below: 

 

pdpa() 

Activate and deactivate a PDP context for TCP/IP over GPRS 

ipo() 

Open a UDP or TCP socket for data transfer 

ipc()  

Close a previously opened UDP or TCP socket 

tcpc() 

Connect to a TCP server specifying IP address and port 

tcps() 

Send data over a previously connected TCP socket 

tcpr()  

Receive data over a previously connected TCP socket 

udps() 

Send data over a UDP socket 

udpr() 

Receive data over a UDP socket 

ipi() 

Obtain IP-related information associated with the GPRS link 

iprh() 

Perform a text-to-IP-address hostname resolution 

 

For full details of these functions, their parameters and 
possible return values, refer to the syntax data in the 
M2

m

power IDE Help files. 

The majority of the functions, with the exception of the 
tcpc() function, will only return once the requested 
operation is complete. More detail regarding tcpc() is 
provided in later sections of this application note. 

 
 
 

LZT 123 8019 R1A

  

Summary of Contents for Embedded Applications

Page 1: ...Application Note Embedded Applications Using the on board TCP IP stack...

Page 2: ...Mobile Communications reserves the right to make modifications additions and deletions to this manual due to typographical errors inaccurate information or improvements to programs and or equipment a...

Page 3: ...pt 6 2 2 4 TCP Connect Operations 7 2 2 5 Testing Communications over TCP IP 8 2 3 General Restrictions 8 2 4 Resource Restrictions 8 2 4 1 Packet Buffers 8 2 4 2 IP Fragmentation 9 2 4 3 Performance...

Page 4: ...EMBEDDED APPLICATIONS FCT 1 Introduction This application note describes the use of the TCP IP sack that is resident on the module within the embedded applications environment LZT 123 8019 R1A 4...

Page 5: ...series of functions outlined below pdpa Activate and deactivate a PDP context for TCP IP over GPRS ipo Open a UDP or TCP socket for data transfer ipc Close a previously opened UDP or TCP socket tcpc...

Page 6: ...access to any ICMP features 2 2 2 GPRS Transport for IP In order to use the embedded TCP IP functions a GPRS PDP context must be activated first to provide the underlying IP transport This should be d...

Page 7: ...depending upon the link performance lost packets etc Therefore the tcpc function has been made non blocking to avoid stalling the script for long periods A call to tcpc will initiate a connection but...

Page 8: ...ion requires that the script closes one socket before attempting to open or re open another For the majority of applications the module is only ever transferring data over a single socket so the restr...

Page 9: ...ts are being received The TCP IP stack will especially during busy periods buffer and consolidate transmit data This will sometimes result in data being sent from the radio device in larger units than...

Page 10: ...VD 13 int APPS_IP_TCPSTATUS_BYTE 14 Reset the IP error flag by reading it gtf APPS_IP_ERROR_TRIGGER Err pdpa 1 1 prtf n PDP activate result d n Err if Err 0 Val ipi 0 prtf IP Address x Val Val ipi 1 p...

Page 11: ...0 prtf n Breaking out of receive loop n Complete TRUE Log status monitoring if gtf APPS_IP_ERROR_TRIGGER prtf n IP ERROR d n gtb APPS_IP_ERROR_STATUSBYTE Err ipc SckNum if Err 0 prtf n Socket close f...

Page 12: ...13 int APPS_IP_DATA_RECVD 13 int APPS_IP_TCPSTATUS_BYTE 14 int TCP_NOT_CONNECTED 1 int TCP_CONNECTING 2 int TCP_CONNECTED 3 Reset the IP error flag by reading it gtf APPS_IP_ERROR_TRIGGER Err pdpa 1 1...

Page 13: ...ct occurs n n else prtf n Received d bytes of data n n len Log status monitoring if gtf APPS_IP_ERROR_TRIGGER prtf n IP ERROR d n gtb APPS_IP_ERROR_STATUSBYTE Complete 1 if gtb APPS_IP_TCPSTATUS_BYTE...

Page 14: ...sent by the tcps function TCPSend char cSckNum char cpTxBuffer int ipLen int MAX_TX_ATTEMPTS 20 int TX_FAILED 2 int TCP_BACKOFF_DLYS 2 int iResult 0 iInitLen ipLen iSent 0 iTxAttempts 0 int iReqLen c...

Page 15: ...ers are inaccessible up to 3 are supported or if the domain name does not resolve there can be an overall delay of between 125 and 140 seconds before the iprh function returns During this delay script...

Page 16: ...it Many modern systems use a TTL of 128 but apart from the most complex of routing arrangements a figure of 64 will be perfectly adequate 2 10 2 DNS Name Caching Period The TCP IP stack of the radio...

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