4-4 delays for accessing pc memory, Delays for accessing pc memory – Omron W343-E1-07 User Manual
Page 122
101
Sending Commands From a Host Computer
Section 5-4
77
{
78
else{
79
err_exit(”send error”);
80
}
81
82
/*
RECEIVE FINS RESPONSE
*/
83
addrlen = sizeof(cs_addr);
84
if((recvlen = recvfrom(sockfd,fins_resp,MAX_MSG,0,&cs_addr,&addrlen))
<0){
85
if(errno == EINTR)
86
goto CMND_SEND; /*
RE-SEND FINS COMMAND
*/
87
err_exit(”receive error”);
88
}
89
else{
90
alarm(0); /*
STOP RESPONSE MONITOR TIMER
*/
91
printf(”recv length %d¥n”,recvlen);
92
if(recvlen<14) /*
ILLEGAL RESPONSE LENGTH CHECK
*/
93
err_exit(”FINS length error”);
94
if((fins_cmnd[3]!=fins_resp[6])||(fins_cmnd[4]!=fins_resp[7])
95
||(fins_cmnd[5]!=fins_resp[8])){ /
*
DESTINATION ADDRESS CHECK
*/
96
err_exit(”illegal source address error”);
97
}
98
if(fins_cmnd[9]!=fins_resp[9]) /*
SID CHECK
*/
99
err_exit(”illegal SID error”);
100
}
101
102
103
/*
CLOSE SOCKET
*/
104
close(sockfd);
105
}
106
/*
107
*
ERROR PROCESSING FUNCTIONS
108
*/
109
err_exit(err_msg)
110
char
*err_msg;
111
{
112
printf(”client: %s %x¥n”,err_msg,errno);
113
exit(1);
114
}
115
116
/*
117
*
SIGNAL CAPTURE FUNCTIONS
118
*/
119
recv_fail()
120
{
121
printf(”response timeout error ¥n”);
122
}
5-4-4
Delays for Accessing PC Memory
The time for the response to be received after a remote node on the Ethernet
network sends a memory area read or write command to a PC can be calcu-
lated using the following formula. This time does not take network transmis-
sion delays into account, so it may be extended under some operating
conditions.
Write command delay time (ms) =
Remote node communications processing time + 4 + (0.011 x number of
words written) + CPU cycle time + CPU data set processing time (Refer to
page 96)
Read command delay time (ms) =
Remote node communications processing time + 8 + (0.011 x number of