I see two different parts in this post.

1. Motors and encoders
   Do the stepper motors and encoders work on a SIMATIC? We don’t have the knowledge in handling team about these motor types and enocers. For 5V TTL a TM PosInput module could work. I don’t think, that a S7-1200 could read the encoder values. In case the encoder supply voltage is 5V, an external power supply is required. The motors could be controlled by TM StepDrive. If motors and encoders could be succesfully connected and run with a TO PositioningAxis, we can think about the path planning and control of the robot.
2. TO Kinematics or LKinTRans
   The robot has 5 degrees of freedom.
   a) For robots with more than 4 axes, the KinPlus license and a S7-1518T or S7-1507D TF (Drive Controller) would be required. I don’t know if this makes sense for this simple robot mechanics. But even with KinPlus, the TO Kinematics does not support this kind of Articulated arm. Articulated arm with 4 and six axes are supported, but not the articulated arm with 5 axes. We currently investigate for another customer, if the 5 axes articulated arm can be controlled via TO Kinematics.
   b) An alternative would be the usage of the library LKinTrans. The user has to program the transformations by himself, but does not need a big CPU with KinPlus license.https://support.industry.siemens.com/cs/ww/de/view/109758302

At first we have to clarify point 1 and find out, if positioning axes can be connected to the motors and encoders.

Please investigate on this topic.