Page 15 of 17 Revision 1.1 Aug 2020
Document No. AlarmLine II Digital EN Controller Installation Instructions
Two-wire RS-485 Modbus RTU/ASCII Communications
The Kidde AlarmLine II Digital EN Controller includes a two wire RS-485 Modbus output which can be
enabled to output the status of each zone of Digital Linear Heat Detection cable. The AlarmLine II Digital EN
Controller Modbus output supports the Modbus RTU/ASCII protocol and the following functions:
•
Function code 4 (Read Input Registers)
The request for reading the input registers should be constructed in the following manner:
•
Address of first register to be read (16-bit)
•
Number of registers to read (16-bit)
The AlarmLine II Digital EN Controller will respond in the following manner:
•
Number of bytes of register values to be read (8-bit)
•
Register values (16-bits per register)
The AlarmLine II Digital EN Controller stores the information for each zone of the Digital LHD cable in the
following format:
Register
Description
Possible Values
0
Zone 1 status
-1 or 65535=fault on zone
0=zone ok
1-32767=distance in metres to trigger point
1
Zone 2 status
-1 or 65535=fault on zone
0=zone ok
1-32767=distance in metres to trigger point
2
Zone 1 cable type
1 = T078-V10-A045 (EN78), 2 = T088-V10-A065 (EN88)
3
Zone 2 cable type
1 = T078-V10-A045 (EN78), 2 = T088-V10-A065 (EN88)
If the start address plus the requested number of registers exceed 4, the AlarmLine II Digital EN Controller
will return an ILLEGAL DATA ADDRESS error.
If the request contains a function code other than those supported the AlarmLine II Digital EN Controller will
return an ILLEGAL FUNCTION error.
