Have you reviewed the manual for the Sabertooth: https://synthiam.com/Software/Manual/Sabertooth-Serial-16039

Thanks for the quick reply.

I have read the manual and a lot of the other posts to try to get it working. I notice under the tab of wiring that you quote connecting the 5v grd and s1 to the ezb4, I dont understand when the 5v is output only. I have now obtained the KANGAROO adapter for the sabertooth and some motors with encoders, which Movement Panel should I use to control the two motors? I am building a DR WHO K9 with a differential drive and have noticed that when I tried to use a h-bridge with two small motors that turning ws impossible as it needed more power on the turn, bigger motors were too fast. The encoders should I hope compensate for the torque neded when turning and good speed control in a straight line. Your comments would be very helpful.

Ya, that’s incorrect about the +5 so i updated it.

If you’re using the Sabertooth motor controller, you’d use the Sabertooth Movement Panel from my previous link. I don’t have experience with a kangaroo or how it works with wheel encoders. The only experience I had with some people using a kangaroo was to build custom servo-like behavior from motorized joints.

Does the kangaroo control the Sabertooth by counting wheel rotations to help the robot drive straight? What does the kangaroo do for a Sabertooth with wheel encoders?

I've never used a Kangaroo for wheels. Only with motorized joints. However from what I learned when I was studying how the Kangaroo worked so I could incorporate it into my robot it will watch the feedback device and adjust speed and torque when needed as the unit rolls along. This will keep the speed steady when going up or down hills and over rough terrain. Kinda like the cruise control on your car does.

Tony (Toymaker) did a video a couple of years ago showing this work.  I am not having much success with searching the community lately, so I'll leave finding as an excersize for the student :)

Edit.  Actually  I found it    https://synthiam.com/Question/8542

I have ordered some new motors with encoders attached which should help with the control. Some encoders I tried were using HALLEFFECT sensors and had to have pull up resistors to work, however they were not that good and would work sometimes. Lets hope that the Sabertooth and the Kangaroo combined work so that I can have complete control over speed and direction.

I've never used the Hall encoders with the Kangaroo but have talked to others that have. They had good results with them. However like me they were using them for motor positioning and speed. Maybe quality has a part in it.

I also added resistors and they seemed to help a lot in completing a successful tune. If I remember correctly DE recommends to add them if your encoder is a long distance away from the Kangaroo. It's in the kangaroo manual if you want to check.

Quick update. Silly me I thought I ordered motor/gearboxes with encoders....however the motors drives the bot quite well using sabertooth as a custom movement panel. I have a 50 amp h-bridge coming from that online auction place, as per a certain snow plough built by the boss. that should overcome the control problem I have been having. The sabertooth and kangaroo now seems to work on some small angled motor/gearboxes I intend to use for other functions in the bot. Using the DEscibe software tune function the procedure is very easy and then a servo panel on the ezb4 will contol the motor/gearbox according to the tune settings. Thanks to everyone who has commented, very useful.