Envision Peripherals NV3128 - Manual (Page 36)

NV3128 RS-422A Machine-Control Routing Switch 2-12
Additionally, two jumpers float or ground pins 5 and 9 of interface
connector J40 for further configuration flexibility.
JUMPER FLOAT GND SIGNAL
J29 1-2 2-3* Signal GND
J30 1-2* 2-3 RI (pin 9)
* = DEFAULT CONFIGURATION
Two final jumpers,J500 and J700 , enable or disable the diagnostic
output:
DIAGNOSTICS ENABLE/DISABLE (OBSOLETE)
JUMPER ENABLED DISABLED
J500 1-2* 2-3
J700 1-2* 2-3
* = DEFAULT CONFIGURATION