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GE Total Lighting Control (TLC)
Do you need to integrate TLC systems into BACnet, Lonworks or some other systems ? We have proven solutions. CAS have a FieldServer driver capable of connecting GE-TLC systems to over 110 other protocols. Our solutions include an option which allows you to connect your GE configuration computer via the FieldServer, sharing the connection to the TLC panels.
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The dangers of XML for System Intergators
Just because a system has an XML interface does not mean you can use it. There are some very important questions you must ask in evaluating the usefulness of an XML interface.
XML provides a syntax and structure but imposes no obligation on how it must be used.
Consider the example of spoken language. English imposes rules on syntax and structure but does not oblige you to say anything useful or comprehensible to other people.
Data Transfer using English
- "Give me the data!” is a valid instruction in English
- “Please email me the 2007 sales figures, grouped by territory with a monthly breakdown in tabular format” is also a valid instruction.
Your assistant is likely to respond well to the 2nd instruction and not know how to respond to the first.
The same considerations apply to XML. Now consider an XML example:
Data Transfer using XML
Format example 1
< Data Xfer >
< Send data now ! >
< /Data Xfer >
Format example 2
< poll >
< source >
< nodeId > 22 < /nodeId >
< dest >
< nodeId > 11 < /nodeId >
< nodeName > node_A < /nodeName >
< /dest >
< responseRequirement > dataOnly < /responseRequirement >
< query >
< action > read < /action >
< tableName > Setpoints < /tableName >
< address > 10 < /address >
< length > 3 < /length >
< /query >
< /poll >
Its not hard to see that the success of the query is dependent on the ability of the system to understand the query. Just because it complies with the rules of the XML syntax does not mean the interface will understand it.
Here are some key questions to ask:
1. Is the XML interface implemented using TCP/IP or UDP?
2. What is the XML Schema? The schema provides the structure of the XML packets used to query and respond with system data. It shows how the messages must be formatted and defines the data types of the various message fields (in the world or protocols the schema is equivalent to the protocol specification).
3. All the other normal questions you would ask of an interface – What data is available? How much can be transferred at once? What is the scaling? How are data objects addressed? etc...
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Ethernet Cables – Cat5 and Cat5e
Where do the terms Cat5 and Cat5e come from?
TIA Telecommunications Industry Association, TIA defined standard TIA-568-B which defines the cables and structured or modular cabling systems and termination standards for building and telecom cabling systems.
Cat5 and Cat5e Cable’s What is the difference?
- Very simply put: The 5e cable is tested to a higher standard. A manufacturer may produce a single cable and only test some of it to the 5e standard. The physical characteristics of the cable are no different but the Cat5e’s higher specification makes it suitable for Gigabit Ethernet.
- Whilst we are on the subject what about Cat6 ? Bandwidth is 2.5 greater at 250MhZ and that’s probably the limit with RJ45 connectors. You might be future proofing using this cable but you could also be wasting money. Also remember that Cat6 is a high tech cable and requires connectors and patch cables assembled to meet the standard.
|
Category 5 |
Category 5e |
| Frequency |
100 MHz |
100 MHz |
| Attenuation (Min. at 100 MHz) |
22 dB |
22 dB |
| Characteristic Impedance |
100 ohms ± 15% |
100 ohms ± 15% |
| NEXT (Min. at 100 MHz) |
32.3 dB |
35.3 dB |
| PS-NEXT (Min. at 100 MHz) |
no specification |
32.3 dB |
| ELFEXT (Min. at 100 MHz) |
no specification |
23.8 dB |
| PS-ELFEXT (Min. at 100 MHz) |
no specification |
20.8 dB |
| Return Loss (Min. at 100 MHz) |
16.0 dB |
20.1 dB |
| Delay Skew (Max. per 100 m) |
no specification |
45 ns |
Source: discountcablesusa.com
Ethernet Cable Color Coding
There are two color coding standards. The color coding standard does not affect whether the cable is a cross-over or straight through patch cable. Color does not affect performance or use of the cable.
| Standard 568A |
|
Standard 568B
This is the most commonly used for patch cables. |
| 1 |
White-Green |
|
1 |
White-Orange |
| 2 |
Green |
|
2 |
Orange |
| 3 |
White-Orange |
|
3 |
White-Green |
| 4 |
Blue |
|
4 |
Blue |
| 5 |
White-Blue |
|
5 |
White-Blue |
| 6 |
Orange |
|
6 |
Green |
| 7 |
White-Brown |
|
7 |
White-Brown |
| 8 |
Brown |
|
8 |
Brown |
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BACnet School
FLAVORS OF BACNET
| Flavor |
Application |
Affects you? |
| IP |
- Uses the TCP/IP protocol
- Controller to contoller
- Controller to HMI
- Some field devices
|
On the up |
| Ethernet 802.3 |
|
Being displaced by IP |
| Point to Point |
|
Rare. Expected to disappear. |
| MS/TP |
|
Millions of installed devices. |
Read the Flavors of Bacnet article.
BACNET OBJECTS AND PROPERTIES
Data inside a BACnet device is organized as a series of objects. Each object has a type and a set of properties. There is always at least one object in a device – it is used to represent the device itself . The other objects represent the device’s data.
In practical terms think of a simple thermostat. Our example is a simple device that has a temperature sensor, allows the set point to be changed locally or remotely, has a local remote selection and reports there is an internal fault by reporting its status as normal/abnormal.
Commonly used properties
Object Type:
Popular Object Types: Analog Input, Analog Output, Binary Input, Binary Output.
Instance Number:
A number that must be not be repeated for any other object of the same type.
Name
Present Value:
The current value of the object. BACnet has ways of telling you if the present value is valid – it uses a property called ‘Reliability’.
Read the BACnet Objects and Properties article.
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