Professor ControlNet

Professor ControlNet is a series of Frequently Asked Questions (FAQ) received by ControlNet International and answered by volunteer technical experts who are either ControlNet technical specialists for their companies or active members of one or more SIGs.

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Professor ControlNet questions and answers Click here.

	We are developing a 'generic' ControlNet adapter device. No address switches are implemented. Are there any fieldbus specific parameters which should be kept in non-volatile memory (e.g. MAC ID)? In a previous DeviceNet device of ours, such parameters were Baudrate and MAC_ID. While the DeviceNet Specification is very punctual about 'non-volatile' parameters, we do not see the same requirements in the ControlNet?
	Would using a TDR be a better test of an installation than an ohmmeter?
	What is an acceptable level of noise?
	How can a cable installation be measured for noise level?
	Is there a diagnostic tool available to evaluate traffic on a segment, like a ControlNet sniffer?
	For SA1 and SA2 in the Redundant Coax circuit, is the Harris part number (V30MLA1812TX1884) correct? Are there any special characteristics for this component that I should consider when looking for an alternate source?
	The Redundant Coax circuit shows C7 & C8 to be "Optional, improves EMI performance"
	Why does the NAP receiver use the four 100 Ohm resistor combination of (2*100 Ohm // 2*100 Ohm = 100 Ohm) to produce 100 Ohm
	Do you actually replace the Control and Information Protocol (CIP Layer) with TCP/IP in the conventional OSI stack when you do ControlNet on Ethernet?
	Can you tell me if it is possible to use the ControlNet link to send unscheduled BTR and BTW messages from PLC to analog modules in remote chassis (1794 or 1771) without establishing scheduled connections with the analog module (slot) in RSNetWorx?
	We use coax and two repeaters to configure a ControlNet network with actual length of 3,000 m. What is the maximum number of nodes for this system?
	What is the "Preamble" in MAC frame? How does collision arbitration of messages occur?
	It was stated that the reason that control devices from different manufacturers were not interoperable was because there was not a standard application layer. This is common knowledge. Then it was stated that ControlNet was the solution to that problem, so my question is this: For the definition of "interoperability" to be fulfilled, to my way of understanding it, one CPU must be able to process the information contained in a packet accepted at it's node. So, are you saying ControlNet has the ability to convert GE fanuc files for an Allen-Bradley processor to use and visa-versa? The GE/A-B selection is merely an example, feel free to reference whatever manufacturers apply since ControlNet is said to be a potential standard for the interoperabilty problem.
	It appears that the ControlNet firmware resides in a separate CPU with a real-time kernel. Is this the only way that the higher level portion of the protocol is implemented?
	What class of processor is required? (For example, do memory requirements dictate a x386 class processor or will the compiled code fit into 1Meg so that I can use a fast 186-class processor with a smaller footprint)?
	Was the ControlNet Application Layer software (CI-500) designed for a specific real-time operating kernel?
	Does the ControlNet Conformance Test Software run on Windows95? Is the CN-1000 card the same card as the Allen-Bradley 1784-KTCX?
	The Specifications require that the MAC_ID be entered in decimal. Is there a path from the CPU into the ASIC to set the MAC_ID, or do developers take two BCD switches and modify their outputs to present to the MAC_ID port on the ASIC as binary values equivalent to 1-63 decimal?
	Normally when we produce a product that attaches to serial busses, we package it in a DIN-Rail mountable box to be placed inside a protective enclosure and also in a die-cast box with Circ-Mil connectors and rate the product NEMA-4. This latter package costs more, but can mount, for instance, in a machining center where there is spray from the cutting fluid, along an auto assembly line where there could be leaking brake fluid, or in a grain milling environment where there is lots of dust. The 75 Ohm BNC connectors are not what I would consider to be a sealed connector, certainly not NEMA-4. Normally we would use a gland nut to seal at the entry to our enclosure, but one large enough to pass the connector will not clamp around the (much smaller diameter) cable. How were the Tees intended to work in a dirty environment? Or do users place shrinkable boots around each connector in a dirty location?
	I am planning a large, outdoor ControlNet installation with over 80 nodes and over 15,000 ft of cable for a tank farm application. Do you recommend lightning protection for this application?
	Are there any ControlNet coaxial media that can meet the following environmental control requirements for a fire protection specification in Asia: "Communication media should be able to withstand 250°C for one hour. During this period, there shall be no loss in communication link."
	What is the Specification on the fiber cable for ControlNet
	In the ControlNet Specification, the drop cable length is specified as one meter. Is there a tolerance on the drop cable length? Can the drop length be increased to 2 or 3 meters? If so, would miniature RG59/U be used?
	We would like to use redundant PLCs, with one active and one standby. Is this configuration possible on ControlNet?
	Since the traffic generator product is no longer offered, is there another tool to generate bus traffic?
	We are using a CNA10 ControlNet ASIC in a repeater product. Do we need to obtain a Vendor ID? We are not creating an adapter class product and we do not see how this would apply to a fiber optic repeater mode communication product.
	Is it true that the only coax cable acceptable for ControlNet is RG-6 Quad Shield, or can a dual shield cable be used?
	What coax cables are recommended for ControlNet applications?
	What is the common mode voltage specification for ControlNet coax trunk line?
	Is there a "standard" trunk cable I can purchase that is "pre-assembled"?
	Will the development software (traffic generator, analyzer, etc.) work with the 1784-LCTX card, or does it just work with the 9220-KTCT card?
	Can I use a 1771-CAN scanner card to communicate to my device, or do I need a special PLC-5 processor with a ControlNet port on it?
	Does the 9220-CNA30S example software include the CNA1- ASIC firmware? port on it?
	When can I expect delivery of a starter kit if I were to place an order with you now?
	Are Specifications available on the ControlNet data link ASIC and hybrid dual MAU (particularly pin descriptions and pinout)?
	Is the upper layer sample C source available so we can benchmark it on our CPU?
	What are the noise specs for the ControlNet coax cable?
	What are the noise specs for the ControlNet coax cable? Can we run the coax in a cable tray with power wiring? What are the restrictions? What is recommended practice?