Description of System Words %SW12 to %SW29
Original instructions
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NOTE: For M580 safety, system words %SW12 and %SW13 have a specific meaning.
Detailed Description
Description of system words %SW12 to %SW29:
Word
Symbol
%SW12
UTWPORTADDR
Function
Processor serial port address
Initial State
–
Platforms
M340: Yes M580: No M580 Safety: No(1) Quantum: No Momentum: Yes Premium: Yes Atrium: Yes 
(1)
%SW12 has a specific meaning.
For Premium: Uni-Telway address of terminal port (in slave mode) as defined in the configuration and loaded into this word on cold start. The modification of the value of this word is not taken into account by the system. For Modicon M340: Gives the Modbus slave address of the CPU serial port. Modification is not taken into account. Is 0 if the CPU does not have a Serial Port link. For Momentum: This word contains the slave address for serial channel 0.
%SW13
XWAYNETWADDR
Function
Main address of the station
Initial State
254
(16#00FE)
Platforms
M340: No M580: No M580 Safety: No(1) Quantum: No Momentum: No Premium: Yes Atrium: Yes 
(1)
%SW13 has a specific meaning.
This word indicates the following for the main network (Fipway or Ethway):
  • the station number (least significant byte) from 0 to 127
  • the network number (most significant byte) from 0 to 63
(value of the micro-switches on the PCMCIA card).
%SW14
OSCOMMVERS
Function
Commercial version of PLC processor
Initial State
–
Platforms
M340: Yes M580: Yes M580 Safety: Yes Quantum: Yes Momentum: Yes Premium: Yes Atrium: Yes
This word contains the current Operating System (OS) version of the PLC processor.
Example: 16#0135 for V1.35
%SW15
OSCOMMPATCH
Function
PLC processor patch version
Initial State
–
Platforms
M340: Yes M580: Yes M580 Safety: Yes Quantum: Yes Momentum: Yes Premium: Yes Atrium: Yes
This word contains the commercial version of the PLC processor patch.
It is coded onto the least significant byte of the word.
Coding: 0 = no patch, 1 = A, 2 = B...
Example: 16#0003 corresponds to patch C.
%SW16
OSINTVERS
Function
Internal firmware version number
Initial State
–
Platforms
M340: Yes M580: Yes M580 Safety: Yes Quantum: Yes Momentum: Yes Premium: Yes Atrium: Yes
This word contains the internal firmware version number in hexadecimal of the PLC processor firmware.
Example: 16#0043 for ir 43
%SW17
FLOATSTAT
Function
Error status on floating operation
Initial State
0
Platforms
M340: Yes M580: Yes M580 Safety: Yes Quantum: Yes Momentum: Yes Premium: Yes Atrium: Yes
When an error in a floating arithmetic operation is detected, bit %S18 is set to 1 and %S17 error status is updated according to the following coding:
  • %SW17.0 = Invalid operation / result is not a number.
  • %SW17.1 =Denormalized operand / result is acceptable (flag not managed by Modicon M340 or Quantum Safety PLCs).
  • %SW17.2 = Division by 0 / result is infinity.
  • %SW17.3 = Overflow / result is infinity.
  • %SW17.4 = Underflow / result is 0.
  • %SW17.5 to %SW17.15 = not used.
This word is reset to 0 by the system on cold start, and also by the program for re-usage purposes.
%SD18:
%SW18 and
%SW19
100MSCOUNTER
Function
Absolute time counter
Initial State
0
Platforms
 M340: Yes M580: Yes M580 Safety: Yes Quantum: Yes Momentum: Yes Premium: Yes Atrium: Yes
%SW18 represents the least significant bytes and %SW19 the most significant bytes of the double word %SD18, which is incremented by the system every one-tenth of a second.
%SD18 is incremented systematically, even in STOP mode and equivalent states. However, times when the PLC is switched off are not taken into account, since the function is not linked to the real-time scheduler, but only to the real-time clock. %SD18 can be read by the user program or by the terminal.
For Quantum safety PLC, knowing that the 2 processors must process exactly the same data, the value of %SD18 is updated at the beginning of the mast task, and then frozen during the application execution.
%SD20:
%SW20 and
%SW21
MSCOUNTER
Function
Absolute time counter
Initial State
0
Platforms
M340: Yes M580: Yes M580 Safety: Yes Quantum: Yes Momentum: Yes Premium: Yes Atrium: Yes
For M340, M580, Momentum and Quantum PLCs %SD20 is incremented every one-thousandth of a second by the system (even when the PLC is in STOP, %SD20 is no longer incremented if the PLC is powered down). %SD20 can be read by the user program or by the terminal.
%SD20 is reset on a cold start.
%SD20 is not reset on a warm start.
For Premium TSX P57 1•4M/2•4M/3•4M/C024M/024M and TSX PCI57 204M/354M PLCs, %SD20 is incremented by 5 every five-thousandth of a second by the system. For all the others Premium PLCs, %SD20 is time counter at 1 ms like Quantum and M340 PLCs.
%SW23
Function
Rotary switch value
Initial State
–
Platforms
M340: Yes M580: No M580 Safety: No Quantum: No Momentum: No Premium: No Atrium: No
The least significant byte contains the Ethernet processor rotary switch.
It can be read by the user program or by the terminal.
%SW26
Function
Number of requests processed
Initial State
–
Platforms
M340: Yes M580: Yes M580 Safety: Yes Quantum: No Momentum: Yes Premium: No Atrium: No
This system word allows to verify on server side the number of requests processed by PLC per second.
%SW27
%SW28
%SW29
Function
System overhead time
Initial State
–
Platforms
M340: Yes M580: Yes M580 Safety: Yes Quantum: No Momentum: Yes Premium: No Atrium: No
  • %SW27 is the last system overhead time.
  • %SW28 contains the maximum system overhead time.
  • %SW29 contains the minimum system overhead time.
The system overhead time depends on the configuration (number of I/O...) and on the current cycle requests (communication, diagnostics).
System overhead time = Mast Cycle Time - User code execution time.
These can be read and written by the user program or by the terminal.
M580 Safety Specific Function
Description of system words %SW12 and %SW13 for M580 safety:
Word
Symbol
%SW12
Function
M580 Safety Mode
Initial State
–
Indicates the operating mode of the Copro module:
  • 16#A501 = maintenance mode
  • 16#5AFE = safety mode
NOTE: Any other value is interpreted as a detected error.
%SW13
Function
M580 Safety Mode
Initial State
–
Indicates the operating mode of the CPU:
  • 16#501A = maintenance mode
  • 16#5AFE = safety mode
NOTE: Any other value is interpreted as a detected error.