AW Gear Meters RT-Ex15-Ex - Manual (Page 17)

AW-Lake Company 8809 Industrial Drive, Franksville, WI 53126  web: www.awgearmeters.com
 Tel: 262-884-9800  Fax: 262-884-9810  Email: [email protected]
RT-Ex15-Ex manual rev 6.13.11.docx Revision 3.3.10
17
LIMITS Display Mode
The RT-Ex15 has two programmable limit outputs: L1 & L2. The LIMIT display shows the
function that each limit is assigned to, the value in engineering units at which each limit will
become active or change state, and the current status of the limit outputs. The limit values are
displayed using the KFR or KFT, decimal location and engineering units corresponding to the
limit assignment. A typical display would be:
LIMITS Programming
The Limits are programmed from the LIMIT display screen. L1 and L2 can be assigned to any of
the following functions.
RATE A
GT TOTAL A
RATE A PL CYCLE OUT (Pulse Output)
RATE Limits / Limit MARGIN – To operate a limit based on RATE, select a RATE A
function based on pulse length or gate time measurement. The MARGIN variable is programmed
in engineering units and determines whether the limit functions as an absolute limit or activates
within a margin or “window” around the programmed RATE limit. When the MARGIN is
programmed as zero, the limit will activate whenever the selected RATE equals or exceeds the
programmed value. When a MARGIN value other than zero is entered, the limit will be active
whenever the selected RATE is within the “window” of the programmed RATE limit value plus
or minus the MARGIN value.
TOTAL Limits – To operate a limit based on the JOB TOTAL, select TOTAL A for the Limit
function. The limit will activate whenever the selected TOTAL equals or exceeds the
programmed value. See BATCH TOTAL Display Mode on page 17 for alternate set-up of total
limits.
CYCLE OUT (Pulse Output) – The CYCLE OUT limit function provides an incremental
output signal for a remote totalizer typically at a lower resolution and frequency. Either or both
limits can be assigned to a CYCLE OUT function. Assigning a limit to the CYCLE OUT
function will toggle the state of the limit output whenever Job TOTAL A has incremented by the
programmed cycle amount. The output will remain on until the cycle amount has accumulated
and turn off until the cycle amount has accumulated again as represented in the following
diagram. The total accumulated between a rising and falling edge is the cycle value. The total
accumulated between any two rising edges is twice the cycle value. The cycle value is entered in
engineering units corresponding to the programmed KFT and decimal location. Do not program
a cycle amount that will produce more than ten pulses per second (10 Hz). Consider the
maximum flowrate to determine the resulting output frequency. The frequency produced (in Hz.)
is the actual flow rate in Engineering Units per Minute divided by 120, divided by the CYCLE
AMOUNT.
NOTE: When considering a large cycle amount, keep in mind that any external totalizer will
miss up to at least one cycle amount of accumulation whenever power is cycled to the RT-Ex15.