Help needed replacing Hayward EcoStar with TriStar VS

[esb]

My current pump is a Hayward EcoStar that now trips the Siemens GFCI breaker at startup. I'm replacing it with a TriStar VS for ease of integration with my OmniLogic panel and because it matches up with the existing plumbing.

I noticed that the installation manual for the EcoStar uses two wires for connection to the Hayward control panel (COMBUS / pins 2 & 3). The manual for the TriStar shows those two pins plus pin 4 / common. Is that common connection required? I'm not sure I have an additional wire for that. All of the wiring is underground and I'm not sure I'm going to be able to fish a new wire with more conductors through the conduit.

Are there any additional gotchas or considerations I need to be aware of when making the switch?

 

[ajw22]

Page 9 in https://hayward-pool-assets.com/ass.../manuals/2014-TriStar-VS-TSG.pdf?fromCDN=true shows a 2 wire connection to COMBUS 2 & 3.

The COM wire is optional. The Tristar manual says:

Note: If communication issues are encountered, a third wire may be connected between terminal “4” at the pool control and terminal “COM” at the motor drive to help improve signal quality. If communication issues persist, the third wire may be disconnected from the “COM” terminal as an additional means of improving signal quality.