460-7la12

Join Date
Mar 2004
Posts
55
I'm trying to get a 460-7LA12 analog 4-20 to talk to a 115CPU 943. All I want to do is test the module. I'm new to Siemens block programming.
Is there someone who could walk me through the process of configuring the appropriate block(s)? Do I use STL? DOes anyone have any examples?
We also have an IM306 in the rack but we're unfamiliar with the configuration.


We're using Fastrack PLC Workshop software for S5.

Any help appreciated.

[email protected]

CTG
 
S5 Analog cards

If my memory serves me right the 460 is an analog input card, the 306 is the I/O configuration card fitted with a bank of dip switches.
First the 306:
for each slot in the rack there will be a dip switch on the 306,
configure the 460 card as analog & the address i.e pw128 (analogs start at 128 & upwards).
The analog card also has dip switches for conversion etc. can't remember what these are now as it has been some years as this is old tech now.
as for the program it would be best to create a function block to convert the analog signal into a scaled value i.e 0-150 deg c.
the peripheral word PW128 for example is a 16 bit word & is as follows
bit0 = overflow bit 1 = overflow
bit1 = fault bit 1= opencircuit (if set on dip sw on card).
bit2 = activity bit 1=busy.
bits 3 to 14 = 12 bit analog value
bit15 = sign bit
example
L pw128 get analog input
T fw200 store for extracting status bits
SLW 1 remove sign bit (shift right drops bit 15 off)
SRW 4 shift to remove bits 0-3 (shift left to remove)
T fw202 store analog value in temp fw
L fw200 get original data
L km 10000000 00000000 bit mask for sign bit
AW and the words to extract only sign bit
L fw202 get extracted analog value (0-2048)
OW or the sign bit with it
t fw204 store actual -2047 to +2048
F 201 bits 0 to 2 hold the status bits
Note if 4-20 ma then the value would be +409 - +2048
this could then be scaled 0-150 or what ever you wished
a good idea is to add zero & span to the function as well
Also note that Siemens standard blocks use FW200 upwards for temporary scratch pad areas so only use them within the function & transfer the data to other areas i.e FW0 -199 or a DataBlock
a standard function would be parameterised like this
FB100 Scale
PWIN I W (PW128)
MIN D KF (zero value)
MAX D KF (max value)
ERR O BIT (F 1.0)
OUT O W (FW100)

inside the function it would start
L = PWIN get analog data
T FW200
......
...

...
L FW204 Scaled Value
T =OUT Transfer to FW100)
BE.
This same block can then be called for every analog input
i.e
PB1

JU FB100
SCALE
PWIN : PW128
MIN : +408
MAX : +1000
ERR : F1.0
OUT : FW100

JU FB100
SCALE
PWIN :pW130
MIN :+408
etc.
Now, Depends on the processor used, some S5 CPU's have inbuilt blocks for analog conversion, maths etc. or you can buy them from Siemens.
To get the blocks just download them from the CPU into your project for 115 I think all standard blocks start at FB200 upwards.
Again if memory serves me right these blocks are FB251?
S5 150-155 you would need to buy (or scrounge) the blocks but it is quite easy to create your own.





t fw100 store for analog extraction
 

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