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Hi all,
I need to map a bit-structure into addresses bit area as %MX.
I cannot find a way to do it..
this is the declaration in "Global Variable"
AT %MX0.0 : ;
when compiling always return "only BOOL variable allowed on bit addresses"
how to solve it? I need to map UDT to physical addr to receive modbus command from HMI..define bit by bit will result too boring and will generate too many variable..
Every suggestion is appreciated
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thanks carcrosser.
I've already tried as you suggest, but in that way there is not correspondence bit-bit between %MX and bit of structures..Moreover going online I receive an invalid state for structured variable
I mean: from HMI I need to send bit command to PLC
HMI Command 1-> MX0.0 --> Structure bit 0
HMI Command 1-> MX0.1 --> Structure bit 1
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do you have your visulisation on the PLC or are you using network variables (MODBUS TCP/IP for example)
if you use the visuals on the PLC you can simply modify them in the visualisation screen by selecting the correct variable. there is no need for this to store it on a physical hardware address.
if you use the mod bus, then you require this option, however I'm not sure on the ability to write this variables from the network.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hi all,
I need to map a bit-structure into addresses bit area as %MX.
I cannot find a way to do it..
this is the declaration in "Global Variable"
AT %MX0.0 : ;
when compiling always return "only BOOL variable allowed on bit addresses"
how to solve it? I need to map UDT to physical addr to receive modbus command from HMI..define bit by bit will result too boring and will generate too many variable..
Every suggestion is appreciated
MX is only boolean as far as I'm concerned. use MW instead
so AT %MX0.0
becomes
AT %MW0
bear in mind that
MX0.0 up to MX0.15
combined will fill word 0 as well as MW0
thanks carcrosser.
I've already tried as you suggest, but in that way there is not correspondence bit-bit between %MX and bit of structures..Moreover going online I receive an invalid state for structured variable
I mean: from HMI I need to send bit command to PLC
HMI Command 1-> MX0.0 --> Structure bit 0
HMI Command 1-> MX0.1 --> Structure bit 1
do you have your visulisation on the PLC or are you using network variables (MODBUS TCP/IP for example)
if you use the visuals on the PLC you can simply modify them in the visualisation screen by selecting the correct variable. there is no need for this to store it on a physical hardware address.
if you use the mod bus, then you require this option, however I'm not sure on the ability to write this variables from the network.
I need to use modbus addresing..
I think I found the solution:
I created a function that split an INPUT var into the single bit of the structure as following:
FUNCTION FuntionName : UDT
VAR_IN_OUT
IN : DWORD;
END_VAR
FuntionName .0:=IN.0;
FuntionName .1:=IN.1;
and then when I call FUN in PRG I declare as :
MOTORCOMMAND:=FuntionName(%MD80);
in this way I have:
%MX160.0=MOTORCOMMAND.0
%MX160.1=MOTORCOMMAND.1
%MX160.2=MOTORCOMMAND.2
........
your way is good, as bits are stored as bytes, so you can not put them in a bitaddress.
however you can pack bits into bytes and unpack them again.