The difference between TLS1 and TLS2 is how they lock/release. The TLS1 will require power to release while the TLS2 will require power to lock.
In practical terms, what this means is as follows:
You install TLS2 on your machine. While the machine is running, there needs to be power on the switch to keep the machine locked from operators. If your plant loses power or if you lose the 24VDC signal (using an ESTOP), the doors can be opened.
The opposite is true with TLS1. If you give the switch 24VDC, it will open the door.
The choice depends on how your safety is currently implemented, but we typically advise that you follow fail-safe measures. In other words, we recommend APPLYING 24VDC to open the doors. By doing so, if you have a signal break or otherwise, the door will remain locked and thus safe. Otherwise, it will unlock if the power goes out, or the wire is loose, etc. Therefore, I’d recommend going with the TLS1.