MTS Isolation Service Manifold Controller - Manual (Page 21)

Technical Reference
Isolation Service Manifold Controller Hardware Overview 21
Technical Reference
The ISM controller provides an interface between up to two ISMs, an MTS
controller and up to two HSMs (off/low/high or proportional) to coordinate the
control/timing sequences of all ISM and HSM solenoids.
The ISM Controller:
• Supports +24VDC HSM Low/High HSM control outputs from an MTS
controller for use as ISM control logic inputs.
• Provides the means to pass +24V HSM Low/High HSM control outputs
from a MTS controller through the ISM controller to a Low/High HSM.
• Provides the means to pass a 0-800mA Proportional HSM control output
from a MTS controller through the ISM controller to a proportional HSM.
• Provides +24VDC power for up to three solenoids per ISM (two for the ISM
block and one for the pilot pressure block).
Note If there is an optional pilot pressure block, the same functions in the
following paragraph apply.
The ISM Controller also provides the means to input at a minimum, 2 normally
open contacts: one from a valve position switch on the isolation valve and one
from a pressure switch monitoring the ISM output pressure. Normally open states
for these contacts = isolation valve closed and pressure below the pressure
sensor’s pressure threshold. These inputs are for ISM control logic use to
determine whether the ISM physical states match the ISM commanded states.
The logic will put the ISM and the HSM to the “Off” states if a discrepancy is
detected.
ISM control logic provides two unpowered relay contact output that goes active
(open) in the event of a fault condition in the ISM controller. These outputs are to
be connected to an interlock input on the MTS controller. Fault conditions are as
follows:
• Incorrect isolation valve position output switch state
• Incorrect pressure sensor output switch state
• ISM controller DC power supply failure
• ISM controller logic failure (watch dog timeout of ISM controller
logic)
• ISM controller safe input/output failure
• Incorrect pilot pressure valve position output switch state
• Incorrect pilot pressure pressure sensor output switch state