ESPA 4.4.4

ESPA 4.4.4 is a protocol controlling wireless pagers. It uses ISO 1745, point-to-point on RS232 as data link layer. The AlphaCom can use this in two ways:

• Output: Sends a “start paging” message to a wireless pager transmitter either due to manual action by a user, or by automatic action such an activation of an input (alarm).
• Input: The AlphaCom can be set up to look like a pager transmitter. The AlphaCom inspects the display text and generates events to the Event Handler which do a range of actions. (“Fire Alarm protocol”). The ESPA 4.4.4 message is finally forwarded to one of the AlphaCom’s pager protocol outputs.

Message example

Typical example of a ESPA 4.4.4 message which AlphaCom will send to a paging system (checksum not shown):

SOH 1 STX 1 US 550 RS 2 US CALL ME 101 RS 3 US 3 RS 4 US 3 RS 5 US 3 RS 6 US 3 ETX 

Same message, written as hex-values:

01 31 02 20 31 1F 35 35 30 1E 32 1F 43 41 4C 4C 20 4D 45 20 
31 30 31 1E 33 1F 33 1E 34 1F 33 1E 35 1F 33 1E 36 1F 33 03

It is configurable if AlphaCom requires a “Status information” message in return. It is also configurable which callstatus value which is required to consider the call to be successful (Recordtype 7).

Reference

www.osca-uk.com/ESPA%20444.pdf