The maximum distance between SCSI devices is two meters. This can be increased to six meters if there is only one SCSI device on the bus.
Typically, extender cables are 1 meter in length. So, there could be 6 extender cables between two devices, such as a computer and hard drive.
Note: Both the Peripheral Interface Cable and the Cable Extender have a straight-through pin configuration (1-1, 2-2, 3-3, and so forth), though pins 10, 12-15, 17, 35-37, 39, 40, and 42 are not connected.