CT Bus

Computer Telephony Bus

CT Bus Description

The CT [Computer Telephony] Bus is a Telecommunications bus [Telcom bus] which may be implemented on either a PCI or cPCI card as a sub bus.
The CT bus provides a TDM [Time Division Multiplexing] scheme over PCI and CompactPCI (cPCI) bus architectures. The TDM bus carries real-time voice and fax traffic across the TDM bus that implements 4,096 bidirectional time slots (64 Kbits/sec each). The bus can support up to 2,048 full-duplex calls.

H.100 CT Bus is a mezzanine bus used with PCI.
The bus works over ribbon cables between normal PCI cards connected on a PCI bus.

"The CT Bus is a bit-serial, byte oriented, synchronous, TDM transport bus operating at 8.192MHz. It consists of two clocks, two frame sync pulses, one backup network timing reference, and 32 independent bit-serial data streams. Voice/data transfer on the bus is accomplished by assigning one or more time-slot numbers and bus stream numbers to the sender and receiver(s). At the selected time-slot, the software-selected sender drives the bus and somewhere on the bus, the receiver(s) clock in the data bits.".. "The H.100 specification documents CT Bus Clocks and Synchronization; data bus lines, interface device requirements, data bus timing, clock skew, reset, power on, and other timing requirements; electrical specifications, mechanical specifications including the design and location of connectors, pin assignments, PCB layouts, and cable requirements; support for partial implementations and optional signals; and inter-operation with other buses."
A mezzanine bus would basically a sub-bus in addition to the main PCI bus.

H.110 CT Bus is a bus used with CompactPCI [cPCI].
In this case the H.110 signals travel over the backplane.

"The H.110 specification is functionally identical to the H.100 specification. However, some of the features in H.100 relating to high availability realize their full utility only in the hot swap CompactPCI environment. There are electrical differences between H.100 and H.110 due to the differences between a ribbon cable and a backplane implementation. The CT Bus is defined on 6U CompactPCI form factor printed circuit boards (PCB) and is implemented on the CompactPCI J4/P4 connector. In addition to the topics covered in the H.100 specification, the H.110 specification includes detailed hot swap requirements." Quote obtained from H.100 and H.110 CT Bus for PCI and Compact PCI; ECTF.org

CT Bus Standards

ECTF 'Enterprise Computer Telephony Forum'
No link is provided because the site does not appear to be active any longer.
Editor comment; it's never a good indication for an industrial standard when the organization is defunct.

CT Bus Interface ICs

Both the H.100 and H.110 CT Bus use the electrical requirements defined in the H.100 Specification.
The specification calls for VOL = 0.4v, and VOH = 2.4 volts which are normal TTL levels.
This page provides a list of TTL IC manufacturers, as they relate to this interface.

CT Card PWB dimensions Size
Euro-Card [Dimensions] Form Factor

The 6U Euro card size is used with the H.110 specification [using the J4 connector].
Three styles:
Z1 [Zone 1]: Power/Management
Z2 [Zone 2]: Data Interface (which consist of 5 ZD connectors; each is 4 rows x 10 columns of shielded differential pin pairs)
Z3 [Zone 3]: Rear panel interconnect [Rear Transition Module]

A number of standards use the term Zone to indication the approximate location of connector styles.
However other than to indicate the relative position of a connector, the term does mean much more.
Although, when a zone only uses one connector style, than the term zone does indicate the default connector type.

Engineering tags: CT Bus or Computer Telephony Bus shown on a CompactPCI board form factor.
The CT bus is an industrial Telecommunications Bus used in TDM systems.
As of this last update the signal assignments for the Computer Telephony Bus are not yet provided.
But the physical size or mechanical dimensions are shown in detail, as they apply to the cPCI or PCI boards.

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PC motherboard

Distributor rolodex Electronic Components Electronic Equipment EDA CDROM Software Engineering Standards, BOB card Cabled Computer Bus Electronic Engineering Design Table Conversion DB9-to-DB25.
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Modified 6/13/15
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