Motion Control Resources
9-Pin Feedback Connectors for J Series Servo Motors
by Mike Maroney
Applied Motion Products Posted 11/20/2017
This article is about J Series Servo Motors from Applied Motion Products and a newly introduced variant of the motor design that comes with a 9-pin feedback connector instead of the more familiar 15-pin feedback connector. The details below include how to identify the 9-pin connector, why we’ve introduced this variant, and how it affects the product line.
Where is the feedback connector?
The images below show the location of the feedback connectors on two J Series servo motors, one with a 9-pin feedback connector and one with a 15-pin.
Why offer a 9-pin connector?
The feedback devices of all J Series servo motors provide two signal types: Hall commutation signals, which are used by the servo drive to determine the relative position of the rotor to the stator, and incremental encoder signals, which are used by the servo drive for all closed loop servo functions including the control of the motor’s torque, speed, and position. Figures 1 and 2 show the pin assignments of the 9-pin and 15-pin feedback connectors. Hall signals are designted by the letters U, V, and W, while encoder signals are designated by A, B, and Z.
With Applied Motion Products servo drives, Hall signals are used only briefly at power-up of the drive and then are not used again (until the next power-up). After power-up the servo drives switch over to use the encoder signals exclusively for all servo functions. Because the Hall and encoder signals are not used at the same time by the servo drive it is possible to send those signals over the same set of connector pins: Hall signals can be sent first at power-up of the system, then the system switches to the encoder signals until the drive powers down. Sharing those pins allows us to reduce the number of pins in the feedback connector from 15 to 9.
The pins shared by the two signal types can be seen in Figure 1. Pins 1+4, 2+5, and 3+6 all share a different pair of Hall+encoder signals. Compare this to Figure 2 where we can see that the 15-pin connector has dedicated pins for the Hall signals: pins 3 through 8. This intelligent switching of signal types allows us to remove the 6 dedicated Hall signal pins and reduced the number of pins on the feedback connector from 15 to 9.
There is no torque/speed/positioning performance difference between using 9-pin and 15-pin feedback connectors. For the user the difference is primarily mechanical because the feedback connector is all the user sees. However, there are differences in drive compatibility with the two connectors. 9-pin connectors are compatible only with SV200 servo drives. 15-pin connectors are compatible with SV200 servo drives as well as older BLuAC5, SV7, and SVAC3 servo drives.
Figure 3 shows how to identify the feedback connector of J Series servo motors by looking at the motor part number. A number 3 in the "Feedback Type" position of the part number designates a 15-pin feedback connecor, while a number 4 designates a 9-pin connector.
Connecting a J Series servo motor to one of our drives is easy using the recommended extension cables available from Applied Motion Products. All extension cables are offered in various lengths to suit your installation needs, with custom lengths available upon request. To make cable selection as easy as possible, compatible cables are shown on each motor’s product page such as this one. Simply scroll down to the Recommended Products section to find the compatible cables available for the motor that interests you.