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SiteMonitor Base Unit

The SiteMonitor base unit forms the basis of the entire system. It acts as the main control unit for the SiteMonitor management chain, and also as the device that handles SNMP queries from an IP network.

The current base unit has one Ethernet Jack, one 6p6c SiteMonitor Management Chain jack, and one 12 position removable terminal block for field wiring. In addition, it contains an internal temperature sensor.

The 12 position terminal block has the following pinout:

Note: Pin 1 is the position closest to the Ethernet and 6p6c Jacks.

1 - Relay Common
2 - Relay N.O
3 - Relay N.C
4 - Not Connected
5- Switch Closure Input
6- Switch Closure Common
7- Shunt Metering Input +
8- Shunt Metering Input -
9- 12-24V Power Source 'A'
10 - Power Source Common
11 - 12-24V Power Source 'B'
12 - Power Source Common

The following are specific notes for each connection above:

RJ45 Ethernet Jack:

This is a 10BaseT Ethernet Jack which connects to an ethernet switch or hub. It is how the SiteMonitor base unit communicates with the IP network which is used to send it SNMP commands.

6P6C SiteMonitor Management Jack:

This jack is used to connect additional units to the base unit.The management bus has been designed in a way that both straight and reversed 6P6C cables can be used.

To connect this device to the management chain, simply connectit to a6P6C jack onanother SiteMonitor device with a short jumper cable.

Relay Output (Pins 1, 2 and 3):

The Base unit includes a built-in Single Pole Dual Throw (SPDT) relay. This relay is capable of switching loads of up to 1/2A at 125VAC and 1A at 24VDC. Exceeding the switching capability of this relay will result in permanent damage to the relay and will necessitate non-warranty repair of the unit.

Pin 1 is the common terminal on the relay, and will need to be connected if the relay is to be used. The remaining two relay pins (2 and 3) will need to be connected depending on your application.

Pin 2 is the Normally Open contact. This contact will never be connected to the common terminal (pin 1) unless a command to activate the relay is received via SNMP.

Pin 3 is the Normally Closed contact. This contact will always be connected to the common terminal (pin 1), unless a command to activate the relay is received via SNMP.

When power is lost to the unit, the relay will revert back to it's default state, regardless of any commands received via SNMP, and the state of the relay will not be restored until a subsequent SNMP command is received. As a result, we encourage users of the SiteMontor system to pick the contacts based on what state is desired when the power is off, or recently restored.

Switch Closure Input (Pins5 and 6):

Pins 4 and 5 form a switch closure input, which can be read via SNMP. The intent of this input is to read a relay or switch closure from an external device. For example, a security loop or status output on a device.

This input is not isolated internally and as such, care must be taken to ensure that voltage is not applied to either of the closure input pins. Applying voltage to either pin may cause damage and will likely result in a non-warranty repair, and may result in apotentially hazardous situation.

To use this input, simply connect the switch to be read between pins 4 and 5. A common application for this input is as a security loop. That is, one or more normally closed security sensors, such as a door sensor, or a loop of wire placed strategically through a solar panel such that it has to be cut to be removed, are connected in series to these inputs. In this way, notification can be received when a security event occurs.

Low-Side Current Shunt Input (Pins 6 and 7):

This input is designed to accept an analog voltage input from a shunt or other similar device which has a maximum output voltage of no more than +-100mV (aka+-1/10th of a volt). Care must be taken to ensure that this voltage is not exceeded.

In addition, this input only supports low side shunts. This means that the shunt has to be on the negative side of the circuit, not on the positive side. Using this input with a high-side shunt may cause damage to the SiteMonitor base unit and/or other devices.

!WARNING! This is a non-isolated input. Be careful of what you attach it to.

Power Source Inputs (Pins 9, 10, 11 and 12):

The SiteMonitor base unit (and all daisy chained units which do not have separate power inputs) receive their operating power through these inputs. The unit has been designed to be connected to up to two separate sources of power, so that it will still operate when one of the two sources is unavailable. In addition, the unit will measure the input voltage from each of these power sources and report it via SNMP.

For sites which are connected to a UPS, we expect most users will connect one of the inputs to a source of power derived from the UPS, and the other input to a source of power derived directly from the commercial power source. In this way, you can both monitor the availability of power from the UPS and from the commercial power source, and also be able to continue operation if either the UPS or commercial power is unavailable.

When connecting power to the unit, the voltage on either input should never exceed 40V under any circumstances. Normal voltages should not exceed 35V. This is sufficient for most 12 and 24V DC sites with standard lead-acid or similar battery chemistries. In addition, each power source must be current limited (either through it's design, or with a fuse) to no more than 1.5A

The Positive voltage from power source 'A' should be connected to pin 9. The positive voltage from power source 'B' should be connected to pin 11. The common (negative) of both power sources should be connected to pins 10 and 12. Please be aware that pins 10 and 12 are internally connected to each other. If there is a chance that signficant current will flow into pin 10 and out pin 12 (or vice versa) due to a miswire or short, then these leads should also be fused.


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