Machine cable specification - PH10 systems

Cable resistance is critical to the correct operation of PH10 systems. Detailed below is the cable specification for PH10 motorised head systems.


For machine cables up to 10m in length the following specification will be aceptable:

  • 13 cores of 7/0.2 tinned copper wire covered by 0.25mm PVC. Overall tinned copper braided screen.
  • PVC outer sheath.
  • Nominal OD 6.9mm.
  • Core-screen capacitance (nominal) 160pF/m.
  • Resistance per core 88 milliohms/m.
15 Way ‘D' Type Plug14 Way LemoFunction
1          7/0.22GROUND SENSE
2          7/0.270 VOLT ANALOGUE
3          7/0.212‘A' AXIS FB
4          7/0.240 VOLT
5          7/0.214‘MUX' RELAY DRIVE
6          7/0.2312 VOLT REF
7          7/0.29‘B' AXIS MOTOR/PROBE
8          7/0.213DATUM + LED
9             --                   -
10        7/0.25LOCK MOTOR DRIVE
11        7/0.28‘A' AXIS MOTOR
12        7/0.26‘A' AXIS MOTOR
13           --                    -
14        7/0.21‘B' AXIS FB
15        7/0.210‘B' AXIS MOTOR/PROBE

For machine cables between 10m and 50m in length, the following conductor sizes are recommended.

15 Way ‘D' Type Plug14 Way LemoWire GaugeApprox Resistance 50 mMax Resistance
1224 AWG4.5 ohms8.0 ohms
2722 AWG2.4 ohms2.8 ohms
31224 AWG4.5 ohms8.0 ohms
4422AWG2.4 ohms2.8 ohms
51424 AWG4.5 ohms8.0 ohms
6322 AWG2.4 ohms2.5 ohms
7922 AWG2.4 ohms2.5 ohms
81324 AWG4.5 ohms8.0 ohms
10522 AWG2.4 ohms2.5 ohms
11822 AWG2.4 ohms2.5 ohms
12622 AWG2.4 ohms2.5 ohms
14124 AWG4.5 ohms8.0 ohms
151022 AWG 2.4 ohms 2.5 ohms 

Suggested stranding for 22 AWG is 19/0.16 or 26/0.127. This provides a reasonable degree of flexibility.


Limiting factors for long cables are:

1. Increased cable resistance in motor driven cables reduces maximum torque and speed. Thus for a head rotating with maximum load the time to arrive at position will be approximately 10% longer with 5 ohm conductors.

2. Increased resistance in the 12 volt reference conductor produces a finite error in calibration. Every ohm above the first ohm will produce a position error of approximately 0.15µm. Therefore an upper limit of resistance should be 5.0 ohms, ie. positional error of 0.75µm.

3. Increased resistance in the locking motor drive conductor reduces speed and max torque. Above 5 ohms the motor could become too slow and eventually fail to reach the top of the cam during a lock cycle.


See also