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<== Date ==> <== Thread ==>
Subject: asking for help on s7nodave
From: "=?gb18030?b?s8nN/rvG5a0=?=" <[email protected]>
To: "=?gb18030?b?dGVjaC10YWxr?=" <[email protected]>
Date: Thu, 6 Sep 2018 22:09:17 +0800
Hi,
I am following this guideline to make connection between epics and PLC.
http://metis.ipfn.ist.utl.pt/index.php?title=FUSION_Collaborations/ESTHER/Slow_Control/EPICS_%26_Siemens_PLC_Tutorial
http://oss.aquenos.com/epics/s7nodave/docs/2.1.3/manual.html#recordreference.deviceaddress

In the second link, I think I reach Step4, which means I can type s7nodaveConfigurePollGroup and s7nodaveConfigureIsoTcpPort  command
However, in the first link, I do not understand the part below. Where can I modify the
record(bi, "S7:biI1_5poll") ???????    Than I can visit the record by sequencer program???????
Sorry I got big confused here.

---------------

Poll Groups

All the input records in the database have a SCAN field. The IOC application will scan the value of each record at the interval defined in the SCAN field. For a SCAN field of "0.1 second" of a input record, the IOC application will query the PLC for that record's value once every 100 miliseconds.
However, EPICS treats each query independently, so by setting the SCAN field of every input record in this way, EPICS will query each value thorugh the local network and wait for the response before moving on to the next query, resulting in delayed responses.
The s7nodave library allows records to be assinged to polling groups. All the records in a pollgroup are queried in the same network packet, greatly reducing response lag.
In order to assign an input record to a poll group using the s7nodave library, one must set the SCAN field to "I/O Intr", and the INP field to "@myPLC(PG=[POLLGROUP_NAME]) [PLC_ADDR]". This can be seen in the example below for the PV S7:biI1_5poll.
record(bi, "S7:biI1_5poll")
{
        field(SCAN, "I/O Intr")
        field(DTYP, "s7nodave")
        field(INP, "@myPLC(PG=1s) I1.5")
        field(DESC, "S7 PLC I1.5 Binary Input POLLING")
}
Ommiting (PG=[POLLGROUP_NAME]) will assign the PV record to the "default" poll group.

----------------------------------------------

Sequencer Program

The example sequencer program inside this testS7 is a simple state-machine that monitors the value of a PLC port and sets another port to high or low accordingly. This program sequencer can be seen in the [testS7]/tests7App/src/snctests7.stt file:

program snctests7

double v;
short light;
assign v to "S7:biQ1_0";
monitor v;
assign light to "S7:boQ0_7";
ss ss1 {
    state init {
when (delay(1)) {
   printf("snctests7: Startup delay over\n");
   printf("snctests7: Going to low\n");
} state low
    }
    state low {
when (v >= 0.5) {
printf("snctests7: Changing to high %f\n",v);
light = TRUE;
pvPut(light);
} state high
    }
    state high {    
    when (v <= 0.5) {
printf("snctests7: Changing to low %f\n",v);
light = FALSE;
pvPut(light);
} state low
    }
}
------------------
黄 瀛
 
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************************************************
Ying Huang
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