Panel to ADEM(r) Interfacing

Overview

On various Caterpillar engines, the ADEM(r) system is used to control the engine operation, and the EMIT Brain (Annunciator) is used to monitor and protect the compressor (which falls under the CAT category “Driven Equipment”). In some cases, the ADEM is generically called an ECU (Engine Control Unit). Similar to other ECUs (E.g. older CAT EIS, or Waukesha ESM) the ADEM features a number of connections that are used by the panel to control engine operation- primarily start/stop and speed control.

The interfacing and operation between older “ADEM 3” and newer “ADEM 4” ECUs are similar, but vary in some ways. This document describes how the Brain and/or panel is wired to the ADEM in different cases, and how the control operates.

Start / Stop / Fault Control

The ADEM has signals connected for controlling start/stop of the engine, and return signal(s) for signifying an engine shutdown. These signals vary on different engines, but the only difference from a panel perspective is how the signals are wired. In general, CAT will publish a document describing customer interfacing to the ECU, and the wiring can be adapted to fit the engine requirements.

Brain 🡆 CAT Interface

The Brain is configured to be in a general ADEM-interfacing mode by going to “Outputs Setup” -> “ECU Selection”, and selecting “CAT ADEM”. This tells the system that the logic should be used to drive an ADEM.

There are two signals from the EMIT panel to the CAT panel for run control: the Run/Stop signal and the driven equipment ready signal.

Run/Stop Signal

The Run/Stop signal is controlled by digital out 2 (pin 69) of the Brain, which on the great majority of panels drives relay #CR2. This relay should be ON to run and OFF to stop. On ADEM 3 systems, this can close a normally open contact from DIGITAL RETURN to RUN/START to run the engine. On ADEM 4 systems, there is sometimes an additional STOP input that is wired to the NC side of this relay, and is grounded during stop. On HMI A4 systems, this relay closes a dry contact to run the engine. The scenarios are shown below.

Jumper 1: On a 14280-2001 panel this is from 113B to 112B to supply "Digital Return" to "X". On other panels this jumper is not present, instead normal internal panel wiring supplies "Digital Return" to the common contact of CR2 at all times.

Jumper 2: This is inside the CAT panel from Normal Stop to return

Jumper 1: On a 14280-2001 panel this is from 113B to 112B to supply "Digital Return" to "X". On other panels this jumper is not present, instead normal internal panel wiring supplies "Digital Return" to the common contact of CR2 at all times.

Driven Equipment Ready Signal

This signal tells the CAT panel that the unit is safe to run, and is almost always controlled by Brain digital out 3 (pin 70). The digital output can be configured as the A4 Driven Equipment Ready pin by going to “Settings” -> “Brain” -> “Output Setup” -> “Output to Function Assignment” and then selecting an unused digital output and changing the function to “ADEM 4 DRIVEN EQUIP READY”. This pin will be on when D.E.R. should be in RUN and off (floating) when D.E.R. should be stopped/faulted. Almost always this wires to a relay #CR3 which closes digital return (ground) to the ADEM driven equipment ready. The D.E.R. pin comes on during STANDBY mode and through startup. This allows the CAT panel alarm to be cleared in panel standby state. Normal startup procedure is to hit RESET on the panel, clear the CAT alarm, then press START on the panel.

From the CAT factory, the DIGITAL EQUIPMENT READY is wired to always run with a jumper, which should be removed during panel installation. Some older ADEM 3 systems also have a NORMAL STOP input which should be permanently wired to DIGITAL RETURN.

Note: On some older panels, driven equipment ready was driven from Pin 10 of the Brain. This pin goes to ground when the Brain reaches the full RUN state (and the fuel valve should come on).

CAT 🡆 Brain interface

The CAT panel has one return signal to tell the Brain that the engine is running. On Panel schematics, this is called “ADEM RUN SIGNAL”, and closes a relay to ground. The contact of the relay is wired to digital input 27 of the Brain which is a normal digital input called “ADEM RUN STATUS”.

The coil side of the relay is wired to two terminal blocks. On most ADEM systems, the run signal is grounded during run, so the other coil side of the relay is wired to keyswitch power. On some ADEM systems the run signal is powered during run, so the other side of the coil is wired to ground. Both cases result in a relay that is powered during run. The relay should go from off to on when the unit starts, and the input on the Brain (DI-27) will go from faulted to unfaulted when the relay comes on.

E-Stop

The E-Stop on the EMIT panel has two contacts, one of which is wired to a digital input on the Brain, and the other is wired to the ADEM. This way when the E-Stop is pressed both systems should get the signal.

The panel schematic wiring table shows how the E-Stop ADEM contact is wired on different engines. In general, the connection to the E-Stop on the CAT panel is broken to additionally flow through the EMIT Panel E-Stop. Most ADEM panels have a jumper installed for this purpose that can be removed to add the EMIT E-Stop.

Note: Some ADEM systems have two separate E-Stop loops running through the emergency stop switches’ contacts. One is maintained to ground for a digital E-Stop signal, and the other is maintained to power to supply fuel valve power. In this scenario, it is only the digital ground loop that is broken and routed through the EMIT panel.

Note 2: CG-137 has two e-stop loops in parallel that both have to be broken at the same time. For this engine the E-stop needs three contact blocks to add our E-stop to the CAT loop-- two for the CAT loop and one for the Brain shutdown.

Speed Control

There are two speed control signals to the ADEM: “Idle” signal, and speed target. Each are discussed below.

Idle Signal

Typically, the ADEM has one input that is used to idle the engine when grounded. This is usually called “IDLE/RATED SPEED” on the CAT engine schematic, though for newer ADEMs an input has to be configured to have this function. Some engines will have this pin operate as ground to idle, and some will be ground to end idle instead. During idle the ADEM will make the engine hold idle speed, also called “Engine Lo Idle” in the CAT config.

In the panel there will be an idle relay that turns on during idle, and is typically driven from digital output #4. The relay will come on when the panel is in the "idle" switch position or during an Idle Hold. The common of the relay will ultimately connect to digital return, and depending on the engine another contact (normally open or normally closed) will wire back to the IDLE/RATED input of the ADEM. The wiring table in the back of the schematic shows which pin to use for a given engine.

Speed Target Signal

The Brain can output a target speed signal on one of the analog outs. This can be wired to the ADEM in various ways to control the speed of the engine.

During the Brain “Speed Output” setup, the user selects an output, what type of analog output it is, and what speeds it corresponds to. These settings should match what the engine is expecting.

Newer ADEM systems have both 4-20 mA (current) inputs and voltage input(s) that can be configured as the speed target input. Older systems tend to have only a voltage input for speed. The engines startup special instruction document generally gives the preferred option for speed control input.

• Current Input: When the Brain outputs 4mA, the engine runs at the configured “Min Hi Idle” speed. When the Brain outputs 20mA, the engine runs at the configured “Max Hi Idle” speed. In between, the input target is scaled linearly.
• Voltage input: Typically on older systems, the voltage input expects 0.5v – 4.5v for the min to max speed. From the factory this comes from a potentiometer, which is disconnected. On some engines it uses 0-5v range instead.

Panel Switches

Except on a few very old panels, the panels will have an IDLE/MANUAL/AUTO selector switch and a manual +/- switch. When in IDLE, the Brain will output the minimum speed, and the IDLE relay will be on. When in MANUAL, the Brain will change the output speed as the SPEED+ or SPEED- switches are held. When in AUTO, the Brain will output the configured auto speed- either a fixed speed, or based off of a sensor condition (e.g. suction pressure). If another manual speed knob exists on the ADEM in this case, it should be unwired and removed to avoid confusion from having two manual speed knobs.

EDT (Data) Connection

The engine data translator built into the DCT can pull data from the ADEM and bring it into the EMIT system. On old panels, an EDT module can be added for this purpose. This has two main benefits:

1. The CAT data is available via panel Modbus from the screen along with the compressor data
2. Datalogs will include the CAT data for both long-term logs and shutdown logs to be compared against compressor data

New ADEM systems have one primarily data link- the CAN data link. This is wired to the “ECU CAN” port. This can be wired by directly connecting to terminal blocks in the CAT panel. The CAT wire colors are as follows, and will always be grouped together:

• CAN L: Green
• CAN H: Yellow
• CAN Cmn: Dark Gray

Older ADEM 3 systems have both the CAN data link and the CDL (Cat Data Link), with a variety of data on each. The CAN data link can still be connected as described above, and an additional connection added for the CDL pins. These are connected as follows:

• CDL+ (Pink in the CAT panel): To EDT “CDL” “A”
• CDL- (Purple in the CAT panel): To EDT “CDL” “B”

Termination Resistor Note

Generally the ADEM panel will have a CAN termination resistor plug that looks like this:

This plug should be removed after connecting the CAN bus to the EMIT panel, since the DCT becomes the new end of the network. This assumes the red switch by the ECU CAN port of the screen is terminated (switched up).

Engine Reference

Pins

Pin Name	3600A4 HMI/CG HMI	3500 A3	3600 A3	3500/3600 A4 OCP	CG137 A4 OCP
A: Run Relay Ground	20	29	14	1-20	4
B: Run Relay Power	48	18	4	1-52	13
C: ADEM Start	71 (full encl) 5 (base encl)	16	6	2-93	59
D: Driven Equip Ready	51	17	21	1-51	16
E: Stop	-	-	-	2-82	76
F: Digital Return	5	15	8	1-61	15
G: Return, jump to H	-	40	2	-	-
H: Normal stop, jump to G	-	19	25	-	-
J: Speed Input	10	7	37	2-70	47
K: Speed Common	11	8	38	2-79	51
L: Rated Speed (Ground = Rated)	-	22	22	-	-
M: Engine Failure	-	25	9	2-84	-
N: ESD 1A	23	-	-	-	-
O: ESD 1B	23	-	-	-	-
P: Idle (Ground = Idle)	58	-	-	1-58	58
Q: CDL+	-	13	31	-	-
R: CDL-	-	14	32	-	-
S: CAN+	50	35	33	1-50	3
T: CAN-	34	36	34	1-34	2
V: ESD2A	22	-	-	-	-
W: ESD2B	22	-	-	-	-
X: START/STOP IN	72 (full encl) 47 (base encl)	-	-	-	-

Speed Control Setup Notes

3300 A4

• Uses voltage mode input on 7
• Uses idle pin on 8, ground to idle

Setup notes:

• Remove original speed pot wire at pin 7

3500 A3

• Uses voltage mode input on 7 OR 4-20mA input on 10
• Uses idle pin on 22, unground for idle

Setup notes:

• Desired speed input has to be set with ET as 0-5v or 4-20 mA, as "Desired Engine Speed Input Configuration"
• Remove original speed pot wire at pin 7 if using voltage mode

3600 A3

• Uses voltage mode input on 37 OR 4-20mA input on 40
• Uses idle pin on 22, unground for idle

Setup notes:

• Desired speed input has to be set with ET as 0-5v or 4-20 mA, as "Desired Engine Speed Input Configuration"
• Remove original speed pot wire at pin 7 if using voltage mode

35/3600 OCP

• Uses voltage mode input on pin 2-70
  • There is also 4-20mA input on EIC pin 10 but this is not recommended for use
• Uses idle pin on 1-58, ground for idle

Setup notes:

• 2-70 and 2-70 are Analog Input 3
• "Desired Speed Input Configuration": CAN Input
• "Analog Input #3 Signal Type": Voltage
• "Analog Input #3 Supply Voltage": 5v
• "Analog Input #3 Signal Range": 0-5v
• "Analog Input #3 Data Identification": Desired Engine Speed Command
• "Analog Input #3 Minimum Data Range": 700 or other min speed
• "Analog Input #3 Maximum Data Range": 1000 or other max speed

CG137 A4 OCP

• Uses voltage or current input on pin 47
• Uses idle pin on 58, ground for idle

Setup Notes:

• 47 and 51 are Analog Input 3
• "Desired Speed Input Configuration": CAN Input
• "Analog Input #3 Signal Type": Current for 4-20mA or Voltage for 0-5V
• "Analog Input #3 Supply Voltage": Disabled
• "Analog Input #3 Signal Range": 4-20mA or 0-5V
• "Analog Input #3 Data Identification": Desired Engine Speed Command
• "Analog Input #3 Minimum Data Range": 1200 or other min speed
• "Analog Input #3 Maximum Data Range": 1800 or other max speed

3600/ CG137 HMI

• Uses 4-20mA input at 10
  • There is also a voltage input at 15 but it is not recommended
• Uses idle pin at 58, ground for idle

Setup notes:

• "Desired Engine Speed Configuration": 4-20mA input or 0-5 VDC depending on pin
• "Secondary Desired Speed Input": Not installed
• "Low Idle Speed": 550 or as needed
• "Maximum Engine High Idle Speed": 1000 or other
• "Minimum Engine High Idles Speed": 700 or other