Arms a counter device. In the case of a detector, it starts accumulating.
Similar to count, but without a preset. Since we do not wait for the armed
device, the state machine does not become BUSY.
Usage: ArmDevice [device]
Usage: ArmDevice [device] [reset]
[device] is the counter device to arm.
An optional argument [reset], if equals 1, instructs the server to reset the counter before arming.