If you wanted to continue using stepper motors, the new ACR7000 is now available. It is low voltage but as most stepper applications are low speed, it may work. The programming is different but similar in text structure. Free video training is online for AcroBasic. See ACR7000 product page for details click here.
Another option is to switch the motor to a servo motor and use the newer IPA or the older Gemini servo (GV6). The IPA uses the AcroBasic programming language and it can certainly do anything the old GT6 could. The IPA has Ethernet TCP/IP communications and 2 analog inputs (no analog outputs) and has additional features (absolute encoder support, lower price than the GV6 and Ethernet/IP for communications with Allen Bradley PLCs via Add On Instructions). The GV6 programming is the same though but an older product .
Servo motors do have advantages of:
1. They're more accurate because they're a closed loop system. Step motors can open loop and can stall/lose position and you don't know it without an encoder; by the time you add an encoder on the back of the motor, you're better off with a servo 99% of the time.
2. They run cooler and are more efficient because they only draw power as needed because it's an error driven system. Thus you're not using very much power when you're not moving; step motors with most drive are running at current when stationary. This makes step motors run hot.
3. Servo motors can run at higher speeds. Step motors top speeds are 50rps (3000rpm) (with very little torque to actually accel/decel the load) if it's a good stepper drive like the Gemini/Zeta. Servo motors can run at 83rps (5000rpm) and higher, increasing your machine throughput and decreasing per part cost.
4. Servo motors are quieter. Step motors are noisy at speeds above 10rps (600rpm).
Very old Gemini's had the option of Profibus: GT6-L5-PB or GT6-L8-PB
or DeviceNet: GT6-L5-DN or GT6-L8-DN
These options have been obsolete for quite some time. The Profibus option are available for existing application re-orders only as custom. For long term replacements requiring Profibus or DeviceNet, the servo Compax3 I20 Profibus is available and the I22 DeviceNet are available.
However, Profibus and DeviceNet are older field bus technology. Most DeviceNet systems have upgraded to Ethernet/IP, where our IPA servo drive/controller is available. The ACR9000 multi-axis controller also has Ethernet/IP as does PAC machine controller and the Xpress HMIs.
Most Profibus systems have upgraded to ProfiNet. The Compax3 I32 ProfiNet is available as standard in Europe, available on request in North America.
The ZETA6000 drive/controller was available to replace the GT6 drives but was discontinued June 2018. The Gemini GT6 may be repairable; contact your local Parker ATC distributor for repair status.
The ZETA6104 is 4Amps and the ZETA6108 is 8Amps, both are 120vac inputs.
The Zeta6000 though is an older product however. It's similar programming language as the GT6 so for low quantity replacements it's one option.
Note, the GT6 had 2 analog inputs and 2 analog outputs. The Zeta6000 does not have analog I/O.