User's Manual

Functional description 337

If no COM ports are available, extra hardware (such as DigiBoard PC/4e

and DigiBoard PC/8e) is required to provide extra serial ports. Investigate

compatibility issues (operating system support, driver available, and so

on) and hardware requirements (memory, available slots, IRQ conflicts,

and so on) before purchasing equipment, or configuring the system.

In some cases, additional hardware is needed, for example, when

RS-232-C limitations apply (for example, at 9600 baud maximum limit of

9 metres). In some cases galvanic isolation is requested, or base-band

modems, SOPHO LAM, CISCO equipment, and so on are needed

to bridge the distance between the DECT Messenger and the alarm

system. In many cases the distance between the DECT Messenger and

the external-paging system is relatively small, so no extra hardware is

needed.

Once a link is established between eESPA and the paging system, the

eESPA handles further communications and informs eKERNEL when

relevant information is to be exchanged.

For a detailed description of the ESPA4.4.4 protocol, refer to the proposal

for serial data interface for paging equipment (Nov. 1984), reference

JMJ182/NB/12B, and ISO1745 Information processing, basic mode control

procedures for data communication systems.

Functional description

In general, eESPA is designed to provide eKERNEL with paging

information. This is carried out using a <msgrqs> message request. For

some interfaces eKERNEL must send feedback to the paging system, a

process that is handled through <msgrpy> message reply request.

Figure 82

msgrqs message request

Every <msgrqs> message belongs to a group and has a specific group ID.

A group contains one or more requests. For every message request in a

group, a data block is created. A data block consists of a header, record

Nortel Communication Server 1000

DECT Messenger Installation and Commissioning — Book 1

NN43120-301 02.01 4 June 2010