Autor Thema: PLC I/O image Xfer  (Gelesen 1445 mal)

Offline Timelord

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PLC I/O image Xfer
« am: November 18, 2014, 13:08:32 Nachmittag »
Hey Guys ,

I needed a full PLC image to transfer (XFER) via the EasyNet
to the other PLC's and the OPC Server.

I only use some 30 Markers in the standard program So
I came up with this :

Set an input or an output on high markers in DW3
In the Easy Software DW3 and DW2 are
DW3 the markers 96 >>> 65
DW2 the markers 64 >>> 49

included zipfile PLC_Image.zip to test.

A double word is 32 bits and within a DW it's converted to a binary numerical string of 32 bits long.
So every Bit (1or0' has the same binary position in the numerical string.
So I send this (32 bit) string via the OPC to the MMC (man machine communtation)
This string is read by theMMC every second (adjustable)
And vice versa
When I set a bit in DW2 out from MMC to DW2 (PLC2)
Say Bit 31 (LSB) then in the PLC2 DW2 gets value '01000000 00000000 00000000 00000000'
This gives me Marker 49 coming out of DW 2.
M49 can be used on any position make/break in the PLC program.
Just be aware that you do .NOT. use --[ m49]-- as coil anywhere else in the ladder.

The problem with MSB or LSB is an inversion of 2x 16 bit from PLC >>> MMC
(something in the 16 bit connection)
Most Significant Bit , Least significant Bit.
So in PLC 2 I start with Q1 >>> Marker 65 which gives me numeric position 
'00000000 00000000 00000000 00000001' in the MMC numerical TAG 19

See picture eaton_forum1.jpg

I put DW2 and DW3 in a table function , this is only needed the pick it up from/to the OPC.
To make them visible towards MMC.

Any questions just ask , I can also try my best German.

Offline Timelord

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Re:PLC I/O image Xfer
« Antwort #1 am: November 18, 2014, 15:12:42 Nachmittag »
By the by ,

A little snag and a tip !!

My PLC3 is an 822-DC-TC version #7 , the other 2 (the PLC2> 822 + PLC1> 819) are version #11.
I cannot transfer a DW out of the old version #7 directly via the OPC server into the MMC

some rerouting !!
First the same routine from plc_image.zip into PLC3

I used a 'Put' DW3 and a 'Get' DW2 on the EasyNet and pick them up with PLC2
From there I xfer them up with the OPC onto the MMC

Works brilliantly both ways.

The ideas for these xfers come from the old DCS systems integrated with GE PLC/DMC's  ver.6

Everybody seems to have forgotten about these old tricks.
It uses hardly any bandwidth so all interactions are very fast.

The ancient tip and trick handbooks  ;)

T L.