Machinery TwinMapping PLC tags to variables
The From Connection mode, addresses, data types, conversions, and update behaviour.
Once a connection exists, wiring a PLC value into the scene is one variable setting.
Setup
- Select the variable, open its Online tab.
- Set the mode to From Connection.
- Choose the connection (by name), enter the address, pick the data type.
| Data type | PLC-side equivalents |
|---|---|
REAL | REAL / LREAL / float |
INT | INT / 16-bit integers |
DINT | DINT / 32-bit integers |
BOOL | BOOL, read as 0 / 1 |
Address syntax is per driver: absolute DB addresses for S7, symbol paths for ADS, node IDs for OPC UA.
Type mismatches read as nonsense, not errors
Reading a REAL address as DINT (or vice versa) yields wildly wrong numbers rather than a failure, the bytes are reinterpreted. If a mapped value looks absurd, check the type first.
Convert units on the variable
PLC values arrive in controller units. Do the conversion on the same variable with its modifiers: scale factor for counts→degrees or µm→mm, output offset for home offsets, min/max as a sanity clamp. Downstream consumers then live entirely in scene units.
Update behaviour
- Values refresh at the connection's polling interval; the scene interpolates nothing, a slow poll on a fast axis looks stepped. Use 50–100 ms for visible motion.
- While the connection is down, the variable holds its last value; the connection's status dot (and Test) tells you why.
Partial mapping is normal
Only map what the PLC truly owns, typically axis positions and a few status bits. Leave derived motion to cams and mechanisms in the twin: a single mapped line-shaft position can drive a whole machine's worth of synchronized cam slaves from the same master.