Monarch Instrument ACT-3 - Manual (Page 14)

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input. Above an input of 31 Hz, the alarms respond within 66 milliseconds. Below this input
they respond within (1 ¸ input frequency) seconds.
The FAST gate time is faster (up to 244 readings per second) but is less accurate (about 0.025%
of reading worst case at high frequencies). Below 244 Hz or 14,640 RPM, the internal update rate
is the period of the input frequency. Thus, the response of the alarms, etc can be seen to be a
function of the input. Above an input of 244 Hz, the alarms respond within 9 milliseconds.
Below this input they respond within (1 ¸ input frequency) seconds.
At input frequencies below 31 Hz or 1860 RPM there will be no difference in the two modes.
The instrument has a special feature to allow it to quickly respond to rapid deceleration and still
measure down to 5 RPM with 1 pulse per revolution. (To measure to 1 RPM, 5 pulses per
revolution are required). After receiving no input pulses for about 67 milliseconds for the
Standard gate mode or 37 mSecs for the Fast gate mode, the instrument will calculate a reading as
though an input pulse had just occurred. If this new reading is less than the last reading, the
instrument uses it. Until an input pulse is detected or the Low-End timeout is reached, the
instrument will “force“ another reading every 33 milliseconds. These “forced” readings will
update the analog output, limits, and the max/min. The last “forced” reading of every ½ second
will be displayed every ½ second. The Low-End timeout can be set to 12, 1 or 0.5 seconds. Refer
to Section 6.13 for details.
4.0 FRONT PANEL
Refer to the front cover for a photo of the front panel.
The front panel of the instrument has a 5 button keypad, five 0.56” 7 segment light emitting displays,
and six single light emitting diodes (LED’s), marked LIM 1, LIM 2, GATE, MIN, MAX and RPM.
Some of these LED’s may not be visible; it depends on the mode the unit is in.
4.1 Status LED’s
4.1.1 LIM 1 and LIM 2 (Alarm) LED’s
The LIM 1 and LIM 2 (Alarm) LED’s indicate the status of the limits, particularly of the
alarm output relay. When an alarm trips, the corresponding LED blinks at a rate around 1
flash per second. When the alarm resets, the LED goes out. These LED’s also go on
continuously to indicate when and which limit is being set or adjusted. If the LED’s are on
continuously, the value on the display is a set point value, not the input value.
4.1.2 GATE LED
The GATE LED is an indication of the instrument’s input trigger signal from a sensor. It is
triggered on by the falling edge of an input pulse, and goes off about 150 milliseconds later
(unless there is another input pulse). It is more useful at slow speeds, as it appears to be on
continuously at higher inputs. It gives an indication that a valid input trigger signal is
present.
4.1.3 MAX and MIN LEDS
The MAX and MIN LED’s indicate to the user that a maximum or a minimum is being
displayed. If either one of these LED’s is on, the display is a stored value, not the input
value.
4.1.4 RPM LED
The RPM LED indicates that the RPM Mode (frequency x 60) has been selected, which can
only be used when the input is one pulse per revolution. The RPM LED is off in all other
modes. In the Scaling Mode the read outs may be in RPM, but the RPM LED will be off.
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NOTE: An ACT-2A will return to the main menu item DIAG at this point.
The next test is for the relays. Press the SET button to turn on relay 1. The display will show
1 on. Press the RESET button to turn off relay 1. The display will show 1 off. Press the UP (
∧∧∧∧∧)
button to turn on relay 2. The display will show 2 on. Press the DOWN ( ∨∨∨∨∨) button to turn off
relay 2. The display will show 2 off. Press the RECALL button to go to the next test.
NOTE: For an ACT-3A, pressing RECALL will go to the serial port test (see details below).
For an ACT-3 the next test is for the Analog Output. Press the SET button to test the zero scale
(0 Vdc or 4 mA). The display will show 0 dA. Press the RESET button to test the half scale (2.5
Vdc or 12 mA). The display will show HALF. Press the UP (
∧∧∧∧∧) button to test the full scale (5 Vdc
or 20 mA). The display will show FULL.
For an ACT-3 press the DOWN ( ∨∨∨∨∨) button to test the serial port, if one is present, otherwise it
will do nothing. Make sure the following connections are made on the RS-232 interface connector:
Pin 2 connected to Pin 3, and Pin 7 connected to Pin 8. The unit will respond with a “Pass” or a
“Fail” message. For an ACT-3 press the RECALL button to go back to the main menu. For an
ACT-3A press the SET and RESET buttons to go back to the main menu.
7.0 PULSE OUTPUT
NOTE: The pulse output is not available on the ACT-2A.
The Pulse Repeater output provides a conditioned TTL positive going 5 V pulse out for each pulse in.
Connect the Positive signal wire (+5 V pulse) to the terminal marked PO and the Common to the
terminal marked COM (to the right of the terminal marked PO). The terminal marked AUX is not used.
See Figure 4 on page 7 for connection detail.
8.0 SERIAL OUTPUT
The ACT-3A and ACT-3 have RS232C compatible serial interfaces. The interface is made via a 9 pin
subminiature D connector on the rear panel. See Appendix D for connection details.
The Receive Data In and Transmit Data Out line are the communication lines between the instrument
and the terminal or computer. The Clear to Send and Request to Send Lines establish a means for the
instrument and computer to indicate when to and when not to send data. The Clear to Send line will
be active (Pin 7 Positive) when the instrument is ready to accept data. Similarly, the instrument will
only send data to the terminal or computer when its Request to Send line is active (Pin 8 Positive).
The instrument sends various information out through the RS232C interface. Under normal operation,
the status of the limits is sent as each event occurs. The user can also request the actual value of the
display be sent on a continuous basis. The user can also request the minimum and maximum values be
sent on demand, as well as the current set up of all parameters of the instrument.
The instrument is fully programmable via the RS232C interface. The user can remotely set the modes,
limits, hysteresis, scale factors and so on, as well as reset either or both the limits.
8.1 Data from the RS232C Interface
The messages below are sent from the instrument as each event occurs. Other information is sent
on demand and is covered in the following section.
NOTE: No information will be sent if the Request to Send line (Pin 8) is inactive (Negative).