Multiple fieldbus interfaces... how to specify which one in the signal declaration?

What KSS version?

There are only a fixed number of $INs and $OUTs, and each one can only be assigned to one Fieldbus. Which $INs/$OUTs are connected to which Fieldbusses is controlled from IOSYS.INI (KRC2) or in the WorkVisual IO Mapping screen (KRC4).

So you might dedicate $IN/$OUT 1-128 to FieldBus 1, and dedicate 129-256 to FieldBus 2, and so on. The one rule is, the assignments cannot be allowed to overlap.

Yeah, for a machine that old, definitely IOSYS.INI.

...hm. Looks like the tags only appear at the very bottom of a page, below all the social-media links. Which would explain why I never see them...

what...?

you map physical I/O from whatever bus to a logical I/O

logical I/O are I/O that robot programs can use, such as $IN[1..8192], $OUT[1..8192]

you cannot have two fieldbuses mapped to same logical I/O

at this point it does NOT matter what the physical I/O or fieldbus is connected, all programs can see are logical I/O. but working with I/O addresses directly is a bad idea. it may be tempting on a project with only a handful I/O such as in school lab. but that's about it....

this is hard.....it is easy to make mistake... code is not documented.... messages are not commented... and this is a nightmare to maintain or troubleshoot. in one word - unprofessional.

SIGNALS are simply aliases or "nicknames" for logical I/O. there is nothing to force you to create fieldbus specific signals.

suppose you have $IN[1] mapped to some DeviceNet input.

You can create bunch of signals such as

SIGNAL DeviceNetInput1 $IN[13]

SIGNAL ProfiBusInput1 $IN[13]

SIGNAL EtherCatInput1 $IN[13]

despite different name, they are all the exact same thing.... because they still point at one and same logical I/O ---> $IN[13]

when input 13 is true, all of those signals are true

when input 13 is false, all of those signals are false.

Btw it makes no sense to name the signals like that. Signal names are supposed to indicate signals FUNCTION, not type of fieldbus, size or color of the wire, brand of sensor etc.

For example:

SIGNAL GripperOpen $OUT[1]
SIGNAL GripperClose $OUT[2]
SIGNAL GripperIsOpen $IN[6]
SIGNAL GripperIsClosed $IN[7]
SIGNAL ConveyorIsRunning $IN[4]
SIGNAL ConveyorSpeedSet $OUT[17] TO $OUT[24]
SIGNAL ConveyorSpeedAct $IN[9] TO $IN[16]

This allows you to write entire program using signals only - without ever mentioning single I/O address. And THAT is the real goal. Program becomes READABLE and MAINTAINABLE.

For example:

1. WAIT FOR GripperIsClosed; generates message that is READABLE to everyone. messages like "Waiting for $IN[3174]" tell NOTHING about FUNCTION of mentioned input.

2. when one of the I/O module fails or gets replaced, you don't have to rewrite whole program. just move wire from dead input or output to a spare one (or new module) and change SIGNAL declaration. that means change in ONE place rather than sifting through heaps of code and editing potentially many files.

3. when program is deployed to another robot with different fieldbus and I/O configuration, you just map your signals according to connected I/O. your program still works - don't have to change a thing.

4. if you are doing simulation (either in OL, OPS or on real robot that does not have rest of the cell connected yet), it is possible to replace file with SIGNAL declarations with alternatives such as BOOL etc. variables. Then you can control them either manually or using background process to make realistic tests - when GripperClose is set and GripperOpen is not, turn on GripperIsSet after small delay. Then you can test failure modes (for example actuator stuck, or input disconnected etc.) all without having complete cell in front of you.

5. convenient bit level access, etc.

SIGNAL ERROR_CODES $OUT[201] to $OUT[208]
SIGNAL ERROR_CODE_Bit0 $OUT[201] 
SIGNAL ERROR_CODE_Bit1 $OUT[202] 
SIGNAL ERROR_CODE_Bit2 $OUT[203] 
SIGNAL ERROR_CODE_Bit3 $OUT[204] 
SIGNAL ERROR_CODE_Bit4 $OUT[205] 
SIGNAL ERROR_CODE_Bit5 $OUT[206] 
SIGNAL ERROR_CODE_Bit6 $OUT[207] 
SIGNAL ERROR_CODE_Bit7 $OUT[208]