AlphaNet Data Protocol

Introduction

To the reader

The purpose of this document is to specify the Data link, Network and Application layer of the AlphaCom Data Protocol.

• The protocol is used for communication in an AlphaCom Network that may comprise several AlphaCom and TouchLine exchanges.
• The protocol is also used between the AlphaCom exchange and external devices, such as Remote I/O boxes, PC based Control Handler systems etc.

The Data Protocol is made generally available from software version AMC 06.00. Previous AMC softwares are NOT compatible with this protocol document.

Word list

The following concepts are commonly used in the document: Module: One AlphaCom “card cage”, contains up to 26 circuit boards (such as ASLT, AMC, APC, AGA). Exchange: Up to 4 AlphaCom modules interconnected in a master/slave configuration. One of the modules plays the role as a master, while the other modules are slaves. Communication with the world outside (if other devices are connected) is via the master. Node: The address of an Exchange. If several exchanges are interconnected (via the AlphaCom Data Protocol), then each exchange will have a unique node number. Device: Examples of device types are AlphaCom module, RIO, AlphaPro, Control Handler. All such devices have a unique device address when interconnected. The AlphaCom and AlphaPro have fixed device address, while the device address of e.g. a RIO is configured (inside the RIO) for the particular application.

History - the MPC protocol

The TouchLine exchanges had a simple data protocol, initially output_only to send information to Intelligent Stations (LWT). The protocol was readable ASCII, in a broadcast mode, and no checksum. It was debugged by hooking up a VT100 terminal. Later on a data command input was added (which had a different format from the output messages). The protocol was used for several purposes: • Station emulation, i.e. digit dialing, M-key, handset, C-key (LWT, ITS, CRM, MLH) Monitoring of events related to this station (dialing to display, conversation partner, transfer destination, call request etc.) • Monitoring of events related to many stations in the exchange (busy, program, line errors) Presented on DAKs (ITS) or screen (CHS) • Additional functionality for the exchange, where an external computer would look for certain station actions, and take control from there (SVM) The exchange has some functions purely for data communication, e.g. directory numbers with DigitDataTransmission ref-info which did nothing except sending out station keypresses. Also, the data command X re-transmitted the incoming data on the broadcast output, thus allowing different data devices to communicate via the exchange (SVM updated DCB absence info). The AlphaCom supports a subset of the MPC protocol for backward compatibility. This allowed some TouchLine generation equipment like PNCI, MLH and CRM to be used with the AlphaCom.

The present and future - the AlphaCom / AlphaNet protocol

When the AlphaCom was designed, a decade had passed since the MPC protocol was designed, and it was decided to make a new protocol with modern properties: • Binary format for speed. Readable ASCII hex format can be used as an alternative for easier debugging. • Data link layer with message checksum for reliability, and with acknowledgment and re-transmission of erroneous messages. • Network layer for routability when several exchanges are connected. • Variable length fields and optional fields so that the protocol can be used also in future systems with different requirements regarding number of digits in addresses, station numbers etc. • A systematic way of addressing exchange resources both as directory numbers and physical addresses. • Addressed messages. Commands are addressed to a specific device, and response is returned to the device issuing the command only. In addition, there is a few status broadcast messages. • Addressed messages can be routed in a network. The input and output messages have identical frame format, and thus can be sent via transit exchanges. The same protocol is used both to control a single exchange, and as the AlphaNet protocol.