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1. Logical Device/Register Number
Every time we customize an ISU system we maintain the Number ranges for Logical
Device number and Logical Register Number once (if mass migration of devices is not in
play).
In general Business processes we do not see them because as SAP says they are used for
internal processing. We can see them though at table level once the Device is installed in
the Installation or also in the Installation Billing View.
Most of the important tables like below have the data linked with the Logical Device and
Register Number along with the Installation and Equipment.
EADZ: Multiple Installation Billing Data – Register Level
ETDZ: Technical Data for Installed Register
EASTS: Billing Data – Installation Structure at the Register Level
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2. EGERH: Historical Data of ISU Device Master Record
ELWEG: Street Route
EQUZ: Equipment time Segment
When devices are created they do not have any logical device number or register number
allotted. During replacement of devices, the new registers adopt the logical register
numbers of the corresponding registers of the removed device. If the devices to be
replaced do not have the same number of registers, new logical register numbers are
added or the logical register numbers that are no longer required are deleted. A
technical removal ends the history of logical registers unless they are passed on to
another device.
So below I have carried out the same process in 2 ways:
First I have carried out the Full Replacement with a similar device. We can see that the
Logical device number and Logical Register Number are not changed for the 2 devices.
Second I broke the replacement process, so did a Removal of the old device and then
installation of the new device. Here we can see that a new Logical Register Number was
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3. generated and a Logical Device Number too.
Now if I add another register to the device while doing the replacement and also change
the logical number as shown below I see that the Logical Register Number and Logical
Device Number have been changed.
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4. Now we see a dummy logical register number in the Display Logical Register Number
screen. The actual logical register number is shortened here just for processing reasons.
This is done when the screen is called. The logical register number is symbolized by a
four-digit dummy number. The function module is ISU_O_LOGICALREG_OPEN (line
766).
It is said that the register of the old device and the register of the new device must have
identical logical register numbers because:
1. Billing data is transferred to the new register.
2. The billing component must know which register is to take on the function of the old
register.
So we shall see the main impact of changing the logical register number during
replacement, below is an Installation with a single demand register.
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5. Now replacement has happened without changing the logical register number as shown
below.
The demand consumption for the first device when removed was 50KW and for the
second device when read was 20 KW. Billing is done for the period, we see a single
billing period with the average of the 2 demand consumption i.e. 35KW.
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6. Now we execute replacement by changing the logical device number as shown below.
This time we see that the system has considered the demand values of the devices
seperately and calculated values accordingly.
So the billing data is not transferred to the new register in this case because of the
change of the logical register number.
Thank You :)
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