Technical Specifications

579
Controller Configure Tab
Reverse mode is a rarely used option and may cause unexpected
results in the event of a power or air failure. Be sure you under-
stand the operation of the SVI in reverse mode before selecting
either hardware or software reverse. Call Masoneilan’s technical
support if you are unsure of the proper use of reverse modes.
In the software reverse mode, care must be taken to insure that
the controller does not output a signal less than 3.8 mA. As the
input signal drops, the air pressure to the actuator increases. How-
ever, below 3.8 mA, the SVI would not have sufficient power to run.
When power is insufficient to run, the output to the I/P would drop
to 0 and the air pressure would go to atmosphere pressure. See
also Fail Low / Fail High.
Fail Direction
This selection determines whether the SVI fails to low output signal
or to high output signal. It is used almost exclusively in the hard-
ware reverse mode. Fail low is the normal mode, but for hardware
reverse instruments, fail high may be preferred. Where fail high
results in a low actuator pressure. In an electrical failure, the SVI no
longer operates and cannot fail high.
Process Controller On/Off This option allows operation of the process controller when
checked. If selected, the process variable must be connected to the
auxiliary input channel and some hardware connections must be
changed (see operating manual). This option can only be selected if
the device has been purchased with the process controller option.
If the device is not used as a process controller uncheck the box.
When OFF, limit switches can be attached to the second input ter-
minal (see operating manual for connection details). The SVI
reports whether the limit switches are open or closed.
Air-To-Open Electrical Failure Air Failure Sensor Failure
Direct Closed Closed Configurable
Hardware Reverse Open Closed Configurable
Software Reverse Closed Closed Configurable
Air-To-Close Electrical Failure Air Failure
Sensor Failure
Direct Open Open Configurable
Hardware Reverse Closed Open Configurable
Software Reverse Open Open Configurable