# CAN termination

A CAN bus needs a 120 Ω resistor at each of its two ends. The gripper's driver has one, on a switch that is
reachable through an opening in the stepper cover: slide it to the **ON** mark to connect the resistor, away from
it to disconnect it.

![The termination switch of the driver, seen through the stepper cover](https://docs.source-robotics.com/MSG-gripper-docs/1.2/assets/Gripper_termination.jpg){ width="700" }

| The gripper is | Switch |
|---|---|
| the last node on a robot's bus, at the end of the arm | ON |
| alone on a bench bus with the CANvas adapter (which has its own termination) | ON |
| in the middle of a bus, with other nodes after it | off |

A bus with the right termination measures about 60 Ω between CANH and CANL with everything unpowered. A missing
or doubled termination shows up as lost frames and a gripper that answers only sometimes.