Hey David,
when you say you have an Huanyang HY01D523B, why is it a Isacon ASKPOWER A131 instead?
Could you please, in cases of such help requests, post an image of the VFD nameplate, e.g. like here or here or here. That is good practice in hardware support forums.
Seems with the link Atroz provided you have a RJ-45 connector somewhere for the serial communications interface:
The pin designation labeled “PC” oviously refers to DB-25 modem port on PCs:
| Name | Typical purpose | Abbreviation | DTE | DCE | DB-25 pin |
|---|---|---|---|---|---|
| Clear To Send | DCE is ready to accept data from the DTE. | CTS | in | out | 5 |
| Transmitted Data | Carries data from DTE to DCE. | TxD | out | in | 2 |
| Received Data | Carries data from DCE to DTE. | RxD | in | out | 3 |
This pin assignment is not to use for the 25-pin I/O port on the buildbotics-derived Onefinity Controller!
So you need a crimp pliers for a 8P8C Modular Connector and a few meters of telecommunications cable.