Page 146 - Gas Detection Systems Training Manual

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;
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.
SEC 3120 16-bit Modbus Manual Page 45 Of 46 Sensor Electronics Corporation For Version 1.2 and above December 2012 P/N 1580282, Rev. 1, 20121228