ECM NH3 5250, Instruction Manual, Page: 9 / 62

5
How to Use
Hooking up the NH
3
5250
The NH
3
5250 kit consists of 4 parts:
1. The display head
2. The module(s)
1
3. The sensor(s)
4. Cabling
The NH
3
5250 is unique in that it puts a control module close to the NH
3
sensor. There are
several advantages of doing this; the main ones are: improvements in signal-to-noise ratio,
multi-channel capability, simplified cabling, and an almost unlimited sensor-to-display head
distance.
The cable between the display head and module(s) is called the EIB (ECM Instrument Bus)
and carries signal and power. There must be a termination resistor at each end of the EIB.
The EIB can be powered at either the module end (Figure 1) or the display head end (Figure
2). To minimize the power voltage drop on the EIB, it is preferable to power the EIB from
the end closest to the module(s) because that is where most of the power is being consumed
(by the NH
3
sensor).
Branches/drops to display head(s) and module(s) are made from tees attached to the EIB. Up
to 32 display heads and modules (total) can exist on the same EIB. The EIB cable, tees, and
termination resistors are industry-standard Eurofast 12 mm. The EIB can be extended to a
length of 100 m.
The NH
3
5250 can be turned on and off by the PWR button on the front of the display head
or by a voltage signal (2.7 - 32 V) applied to the KEY connector on the back of the display
head. The current requirements of this voltage signal are very low (100 µA).
After being turned on, the display head will test both displays and all leds and then show:
1. The display head’s serial number
2. The version of the display head’s software
3. The calibration date of the display head (MM.DD YYYY)
4. The serial number (see Figure B1) of the NH
3
module assigned to the upper channel
and the serial number of the NH
3
module assigned to the lower channel.
“….” means no NH
3
module has been assigned to the channel.
5. Parameter data from the NH
3
module assigned to that channel.
Figures 3 through 5 show details and part numbers of components in Figures 1 and 2.
Optional components are also shown.
1
Modules can be setup in EIB Mode or Stand-alone Mode. When the modules are used with a display head,
they must be in EIB mode. See Appendix B for more information.