Conceptual View of the RMC Module

The flexibility of the RMC software and hardware al
lows a large range of configurations. Acquiring a bet-
ter understanding of the controller’s overall function-
ality and capabilities while at the same time plan-
ning out how the controller can be used will deliver
maximum effectiveness in your application.

The RMC can be connected at the system level to
as many as 17 modules, one of which can be an Ac-
cess module and the others (16 maximum) can be any
combination of available modules. The user will de-
fine each address via the button on the face of each
module. Each installed RMC module must have a
unique Standard Bus address ranging from 1-9, A-F,
where the factory defaults for each is Standard Bus
address 1.

Getting Started Quickly

The RMC (Controller) can be ordered with up to
four PID loops with default loop configurations (all
loops) out of the box as follows:

  • Analog Input functions set to thermocouple, type J
  • Control loops 1-4 use Analog Inputs 1-4
  • Heat algorithm set for PID, Cool set to off
  • Outputs set to off
  • Control mode set to Auto
  • Set point set to 75 °F

To enable a loop for heat simply follow the steps below:
1. Navigate to the Setup Page
2. Once on the Setup Page navigate to the Output

3. Menu and then the output of choice
4. Change the default setting of Off to Heat Power
5. Select the desired loop instance


Zones can communicate with one another over the
backplane (local and split rail). Once the system is
configured and running, changing zone addresses
without careful deliberation may cause disruption in

Some of the user selectable ordering options are
listed below:

1. Class 2 or SELV (Safety Extra Low Voltage) equiv-
alent Power Supplies:

  • 90-264 Vac to 24Vdc @ 31 watts
  • 90-264 Vac to 24Vdc @ 60 watts
  • 90-264 Vac to 24Vdc @ 91 watts

2. RMC Module can provide:

  • 1 to 4 control loops, limits or CT inputs
  • 1 to 9 inputs (various types)

  • 1 to 12 outputs (various types)
  • Modbus RTU communications

As can be seen above the RMC module is fully scal-
able with regards to power requirements, number of
loops, inputs, and outputs.

It is useful to think of the controller in three
parts: inputs, functions and outputs. Information
flows from an input to a function to an output when
the controller is properly configured. An RMC mod-
ule can carry out several functions at the same time,
e.g., PID control, monitoring for several different
alarm situations, monitoring and acting upon Digi-
tal Inputs and driving output devices such as heat-
ers, audible alarms, lights. Each process needs to
be thought out carefully and the controller’s inputs,
functions and outputs set up properly.


Functions use input signals to calculate a value. A
function may be as simple as reading a digital input
to set a state to true or false, or reading a tempera-
ture to set an alarm state to on or off. Alternatively,
if a failure with the primary sensing device should
occur, sensor backup could be utilized to avoid an un-
wanted shutdown.

To set up a function, one of the first things that
must be considered is the function source and in-
stance. For example, if the control is equipped with
Digital Inputs (source) and it was decided to use DI 9
(instance) it can then be associated with an Action to
reset an individual alarm or all alarms. To configure
as such, follow the steps below:

Setup Page (Digital I/O Menu)

1. Navigate to the Setup Page and then to the Digital
I/O menu.
2. Select the desired instance and set the direction to
input voltage or input dry contact.

Setup Page (Action Menu)

3. Navigate to the Setup Page and then the Action

4. Set the Action Function to Alarm
5. Select which alarm instance will be reset (0 equals
6. Select the Source Function to Digital I/O
7. Select the Source Instance (step 2 above)
8. Select the Source Zone (0 equals the module being
9. Select the Active Level to execute the desired func-

This configuration is now complete. When the selected digital input is active the alarm or all alarms that are latched without a currently existing alarm condition will be reset. If a specific alarm instance (1 – 8)
is selected (step 5) it will be that instance alone that
will be reset.

Alarms will reset automatically when the condition
that caused the alarm goes back to a non-alarm state
if the alarm latching prompt is set to non-latching
(Setup Page, Alarm Menu).

Keep in mind that a function is a user-programmed
internal process that does not execute any action out-
side of the controller. To have any effect outside of the
controller, an output must be configured to respond
to a function.


The inputs provide the information that any given
programmed function can act upon. In a simple form,
this information may come from an operator pushing a button, or as part of a more complex function it
stance of that function will drive the selected output.
may represent a remote set point being received from
another zone.

Each analog input can be configured for therm-
istors, thermocouples, or RTDs to read the process
variable. It can also read mV/volts, current or resis-
tance, enabling usage of various devices to read hu-
midity, air pressure, operator inputs and other val-
ues. The settings in the Analog Input Menu (Setup
Page) for each analog input must be configured to
match the device connected to that input.

Each digital input reads whether a device is active or inactive. A RM system can be equipped with
multiple digital I/O. Each I/O point must be config-
ured to function as either an input or output with the
direction parameter in the digital I/O Menu (Setup

Another concept that needs to be understood is
the difference between an input tied to a real-world
device such as a thermocouple and one that is tied to
an internal function.

In the example above the analog input function on
the left is tied directly to the control function where
its internal output is routed to a real-world output.
With a slight modification of the graphic above the
example below now ties the real-world inputs directly
to the control and alarm functions. For the sake of
this example the following is true:

– Two unique high process alarms are configured for
analog inputs 1 and 2
– The logic block is configured as an OR function
– The output function is tied to the internal output of
the logical OR function

When either process alarm is true (analog input value is greater than the alarm high set point, the real- world output will be driven on.


Outputs can perform various functions or actions in
response to information provided by a function such
as: heat power from the output of the control, using a
digital output to serve as a profile event, drive a light
on or off, unlocking a door or turning on a buzzer.

Assign an output to a function in the Output Menu or Digital I/O Menu. Then select which instance of that function will drive the selected output.
For example, you might assign an output to respond to an internal output of a compare function or to re-transmit the value of analog input 2 (instance 2).

You can assign more than one output to respond
to a single instance of a function. For example, alarm
could be used to trigger a light connected to output
and a siren connected to digital output 5.

Input Events and Output Events

Input and output events are internal states that are
used exclusively by profiles. The source of an event
input can come from a real-world digital input or an
output from another function. Likewise, event out-
puts may control a physical output such as an output
function block or be used as an input to another function.


Based on a given input (Digital I/O, Event output,
Logic function, etc..) the Action function can cause
other functions to occur. To name a few, starting
and stopping a profile, silencing alarms, turn control
loops off and placing alarms in non-alarm state.

A Conceptual View of RM Hardware Configurations

Due to the scalability and flexibility in the RM system a user has several options available in the way
that the hardware can be connected. Listed below
are a few examples.

RMC Module Connected to a Remote User Interface (RUI) and a PC

In this configuration the RUI and PC are connected to the RMC module via Watlow’s Standard Bus
where both will be able to talk directly to the RMC

module. The PC running EZ-ZONE Configurator
software and the RUI can be used to configure and
then monitor the RMC module.

RMC Module Connected to a Programmable
Logic Controller (PLC) on a DIN Rail

In this configuration the PLC can be connected to
the RMC module via the Access module using one or
more available protocols:
1. EtherNet/IP and or Modbus TCP

2. DeviceNet

3. Modbus RTU

RMC Module Connected to an Operator Interface Terminal (OIT) through an RUI/Gateway

In this configuration the OIT can be running any of
a number of protocols communicating to the RM sys-
tem through Watlow’s RUI/Gateway. Available proto-
cols for the RUI/Gateway follow:
1. EtherNet/IP and or Modbus TCP
2. DeviceNet
3. Modbus RTU

RM System Connected to a Split Rail with OIT

In this configuration both the Inter-module Bus
(backplane communications) and Standard Bus are
connected between rails to allow for remote capabili-
ties. It is recommended that the split rail connection
not exceed 200 feet. In this configuration the OIT
can communicate with all modules (maximum 16
modules any combination with one Access module).

RM Control Module Connected to an OIT Running Modbus RTU

In this configuration the control module connected
to the OIT is equipped with the Modbus RTU protocol (RMCxxxxxxxxx1xx). It is important to note that
Modbus communications takes place between the
OIT and the control it is connected to. The RM backplane is always using the Standard Bus protocol. If
it is desired that the OIT communicate to both control modules, both control modules would need Mod-bus communications and then pins CC, CA, and CB
would need to be daisy chained together.

Module Orientation

The picture below represents one of six possible RM
modules. All six will have four slots on the face (slot
A, B, D, and E) and one on the bottom (slot C) not
shown. All of these slots are not always used on all
modules. On the face of the module there is a button
white circle) under the Zone address (5) that when
pushed and held has the following functions:

  • For any module, push and hold for ~ 2 seconds. The
    address will intensify indicating that it can now be
    changed. Release and repeatedly press to change
    to the desired unique address
  • For the control module, if equipped with the Mod-bus protocol (RMCxxxxxxxxx1xx) pushing and
    holding this button for ~ 6 seconds will cause the
    display to reflect P for protocol. Releasing the button and then pushing it again (within 6 seconds)
    the display will toggle between N (Modbus) and S
    (Standard Bus). Valid addresses for Modbus and
    Standard bus range from 1 -16 (1 – 9, A is 10, B is
    11, C is 12, D is 13, E is 14, F is 15, and h is 16).
    The Access module is shipped at address J or 17