CSR-20 & CSR-40, September 1999
Electrical Maintenance
Integrated Remote Monitor Unit
5-5
2.
Check for CCU TXD signal at CCU end of MMU-CCU
serial cable, see Step 2 callout on diagram.
a.
If TXD signal is not present, check COM connec-
tions, input power, and ground connections at the
CCU. Repair the connection or replace the CCU as
necessary; see Step 2.A. callouts on diagram.
b.
If TXD signal is present, check for signal at MMU
end of serial cable; see Step 2.B. callout on diagram.
•
If TXD signal is not present, check cable for
continuity; repair or replace.
•
If TXD signal is present, check MMU internal
cable and serial card; repair or replace as neces-
sary.
Problem 2: One or More Containers on the Power
Network Do Not Communicate with the
MMU
•
Symptom: Containers will be listed as DISCONNECTED
or UNPLUGGED. The containers do not appear in the
NET LIST when they are plugged in or do not respond to
an operator request message (STATUS, PRETRIP SET-
POINT, etc.).
•
System Operation: The MMU initiates a mapping request
every minute or two, which the CCU transmits over the
power lines. An Integrated Remote Monitoring Unit
(IRMU) that has just been powered up responds to this
request to identify itself to the MMU.
Problem 2 Diagnosis:
1.
If only one container demonstrates the symptom, check
the input power at the container and IRMU.
a.
If power is OK, plug container into an outlet from
which other containers are communicating.
•
If container now communicates, the outlet is not
part of the power network connected to the
MMU.
•
If container does not communicate, replace the
IRMU.
b.
If power is not OK, determine location of power
interruption and correct the problem.
2.
If several containers demonstrate symptoms, refer to the
NET installation diagram for your unit to see if all the
containers are located in the same section of the NET
a.
If they are not in the same section, diagnose accord-
ing to Step 1a. above.
b.
If they are in the same section, check connections and
fuses for the communication devices that are installed
in that segment of the NET.
•
If OK, consult Thermo King for additional assis-
tance.
•
If not OK, repair connections or replace fuses as
required.
Problem 3: IRMU and Unit Controller Do Not
Communicate
•
Symptom: The message “NO RESPONSE FROM CON-
TAINER NO. CONTROLLER” appears in the status area
of the MMU upper screen every time it is polled.
•
System Operation: The IRMU is located above the com-
pressor compartment. The system consists of a printed cir-
cuit hoard that gathers information from the unit’s con-
troller and transmits that information to a remote comput-
er for operator viewing. The IRMU sends a message to the
controller every 20 to 30 seconds. The controller should
respond to this message. See the RMU Unit Section dia-
gram. Attach voltmeter and oscilloscope as shown on dia-
gram for the following steps.
Problem 3 Diagnosis:
1.
Check for the TXD signal at the IRMU; see Step 1 callout
on diagram.
a.
If signal is not present, replace the IRMU.
b.
If signal is present, go to step 2.
Oscilloscope Readout for Problem 1
Digital Voltmeter O/L Reading (every 20 to 30 sec-
onds) for Problem 3.
Oscilloscope: Check signals on a properly function-
ing unit and record settings of oscilloscope.
