Detcon 700 Remote Sensor/Alarm Relay Module - Manual (Page 9)

700 RAM I.M.
NOTE: Both the 3-wire power/mA cable and the 2-wire Modbus™ serial communications
cable are required when remote wiring between the RAM and the 700 Gas Sensor.
NOTE: The same recommended cables should be used for the connection between a
Modbus™ master control device and the RAM. However, if only the 4-20mA signal is being
used by the master/host controller, then only the 3-wire cable is required.
2. Operator Interface
The operator interface of the RAM is very similar to the Model 700 Gas Sensor. It uses the identical LED
display, same programming magnet, and has the same magnetic programming switches (PGM1/ZERO and
PGM2/SPAN). The main difference is that the 700 RAM has LED indicators for the 3 relays (ALM1,
ALM2 and FAULT) and a CAL LED to indicate when the 700 sensor is in calibration or being polled
serially by a master control device.
The gas reading, gas units, and fault status reported by the RAM will mimic that of the 700 Gas Sensor. The
Modbus™ output from the RAM repeats the Modbus™ output from the 700 Gas Sensor.
NOTE: If the Model 700 Gas Sensor is directly connected to the RAM and junction box, then
the gas sensor operation should be exercised through the 700 Gas Sensor (and not the RAM).
This is the recommended practice since the RAM contains a limited number of sensor
operational control functions. If the RAM and 700 Gas Sensor are separated, then normal
remote gas sensor operation should be exercised through the RAM.
The operating interface is menu-driven via the two magnetic program switches located under the target
marks on the RAM faceplate. The two switches are referred to as “PGM1” and “PGM2”. The menu list
consists of three major items that include sub-menus as indicated below. (Refer to the complete Software
Flow Chart Figure 8)
Normal Operation
Current Reading and Fault Status
Calibration Mode
AutoZero (if applicable)
AutoSpan
Program Mode
View Sensor Status (representative of whichever Model 700 Gas Sensor is attached)
Set AutoSpan Level
Set Serial ID
Alarm 1 Settings
Alarm 2 Settings
Fault Settings
Signal Output Check
The user interface of the RAM is designed to mimic that of the Model 700 Gas Sensor. However, only the
functions deemed critical for normal remote sensor operation are available. The 5 menu functions that are
available for the remote control of the 700 Gas Sensor are:
700 RAM I.M. Rev. 1.0 Page 5 of 13