Note: When the Process Control Loop is enabled, the Analog output voltage is normalized to half of
the total voltage input. For instance, with a 0-5V analog input range such as the RIO-47100 – the
voltage is normalized to 2.5V. This allows the output to go below 2.5 to compensate for a negative
error and above 2.5V to compensate for positive error.
The AQ and DQ must be set on the RIO-47120 to configure the Analog input and output ranges before
the process control loops are run and prior to setting AZ & AF. The range of the PS command is
dependent on the AQ command.
Current vs Flow Control Mode
The PID loop on the RIO-47xxx by default works as a “current” mode loop. This means that when
position error is 0 the analog output will also be set to zero.
Firmware revisions Rev D and newer allow the user to set a negative value for the DB command that
will set the Process control loop into a flow control or velocity mode. When DB is set to a negative
value, the analog output will be held at its current value and the PID’s will be held constant when the
feedback is within the range set by the DB command. This mode is preferable for many fluid and
temperature control applications.
Real Time Clock
The
Expanded Memory
models of the RIO (see Table 1.1 if your model qualifies) are equipped with a
real time clock feature. The real time clock provides true time in seconds, minutes and hours. The RT
command provides a method to set the time and operands to return the current time. The default
real time clock does not persist through a power cycle and must be set whenever power is restored.
The
Expanded Memory
models can also be ordered with a clock upgrade (-RTC) including a higher
precision clock than the default, and a battery backup for the time hardware. All hardware is within
the standard sheet metal footprint. The –RTC clock will continue to run when power is removed from
the RIO. The –RTC option also provides a calendar function including year, month of year, day of
month, and day of week. This feature can be set and queried through the RY command.
Both versions of the real time clock can be set to a TIME protocol (RFC 868) server. Using IH, the RIO
can connect to a TIME server over TCP on port 37 and receive the 32bit response. The firmware will
then set the time and calendar (if applicable) to the TIME server value. The command RO is used to
set the GMT time zone offset for localization of the current time. The TIME protocol synchronization
is designed to connect to a server on the local network. Contact Galil if a local server is not available
(e.g. an Internet Gateway is required to contact NIST).
See the -RTC section in the Appendix for further details and specifications for the real time clock.
Chapter 5 Programming ▫ 81 RIO-47xxx Rev 1.0r