BayTech 24SII Owner's Manual page 54

NOTE: If your EIA-422 device has only one output hardware
handshake line (i.e., no HSO+ and HSO-), connect this single
handshake line to HSI- on the M24SII-V07 module (Pin 5).
If you are connecting a printer port on the M24SII-V07 module to
another BayTech product (such as the Tran-x SP-01 or SP-02) using
4-wire Operation and unidirectional Printer Sharing Mode, please refer
to Appendix A.7.4 for the recommended cable pinout.