Sensor Electronics SEC Millenium Series Instruction And Operation Manual page 146

3. Unique Sensor Role- In this role, all sensors attached may have different gas
types, ranges and detection types. The purpose of this role is consolidate space
and act as a central hub to multiple sensors and logical sub-channels. Alarm relays
may be programmed to operate in any fashion, but typically driven in a logical
"OR" configuration, thus ANY sensor alarm level drives the respective relay.
Sensor faults by any sensor operate the fault relay in a logical "OR" configuration
as well.
· Modbus Effects- since the 3120 (head) operates allowing multiple
sensors having different gas detection types and ranges and sub-
channels;
SEC 3120 16-bit Modbus Manual
For Version 1.2 and above
o The address ALL sensor region (42001 - 42099) will be
ignored and generate exception messages if addressed by a
master. No reads or writes will be allowed.
o All sensor regions in accordance with the number of reported
maximum attached sensors (see unit register 42922) are
independently readable and writeable (42101 - 42899).
o Unit region nine (42901 - 42999) will function normally as
described in this document, unaffected by sensor role.
Page 45 Of 46
December 2012
Sensor Electronics Corporation
P/N 1580282, Rev. 1, 20121228