Slots provide a way to read non-consecutive registers using one read command. When a slot address
sequence (a set of consecutive slots) has been configured, the transmitter automatically replicates
real-time data from non-consecutive addresses into the consecutive addresses of the slots. Without
slots, multiple read commands must be issued to read the non-consecutive addresses; with slots, only
one read command is required.
There are 64 slots: 32 slots used for sets of addresses (Slot Type 1) and 32 slots used for sets of
process variables (Slot Type 2). Each slot has a pre-assigned configuration register (integer) and a
corresponding value register pair. The configuration registers are read-write; the value register pairs
may be read-write or read-only.
For Slot Type 1:
•The configuration register stores a Modbus address. The address specifies the first register of
any two consecutive registers (Registers X and X+1) in the Modbus memory map. These
registers may contain boolean, integer, floating-point, ASCII, or binary data.
•The first register of the value register pair stores the real-time value of Register X, and the
second register stores the real-time value of Register X+1. Depending on the particular
registers specified, the second register may or may not contain useful data.
For Slot Type 2:
•The configuration register stores a process variable code.
•The value register pair stores the real-time value of the assigned process variable. Depending
on the data type of the process variable, the second register may or may not contain useful
data.
See Table SA-1 for a list of the 64 slots and their associated configuration registers and value register
pairs.
Section SA-2 provides instructions for configuring slot address sequences.
Section SA-3 provides instructions for reading slot address sequences.
Section SA-4 provides instructions for using long integers in slot address sequences.
Section SA-5 provides instructions for using binary (double-precision) values in slot address
sequences.
Section SA-6 provides detailed examples of slot address sequence setup and use.
Slots and Slot Address Sequences
Table SA-1 Slot address registers
Slot Type 1Slot Type 2
Address of
Slot
0655687 688751783 784
1656689 690752785 786
2657691 692753787 788
3658693 694754789 790
4659695 696755791 792
5660697 698756793 794
6661699 700757795 796
7662701 702758797 798
8663703 704759799 800
9664705 706760801 802
10665707 708761803 804
11666709 710762805 806
12667711 712763807 808
13668713 714764809 810
14669715 716765811 812
15670717 718766813 814
16671719 720767815 816
17672721 722768817 818
18673723 724769819 820
19674725 726770821 822
20675727 728771823 824
21676729 730772825 826
22677731 732773827 828
23678733 734774829 830
24679735 736775831 832
25680737 738776833 834
26681739 740777835 836
27682741 742778837 838
28683743 744779839 840
29684745 746780841 842
30685747 748781843 844
31686749 750782845 846
configuration register
Address of value
1
register pair
Address of
configuration register
Address of value
2
register pair
(1) Contains a Modbus address.
(2) Contains a process variable code.
2Micro Motion® Modbus Interface Tool
Slots and Slot Address Sequences
SA 2Configuring slot address sequences
To configure a slot address sequence of Slot Type 1:
1. Determine the values that the read command will return, and the order in which they will be
returned.
For example, you might want to read volume flow rate and the volume flow unit.
2. Identify the addresses containing these values.
Volume flow rate is stored in register pair 253–254, and the volume flow unit is stored in
register 42.
3. Determine the slots to be used in the slot address sequence. Each value that the read command
will return requires a separate slot.
To read volume flow rate and the volume flow unit, you need two consecutive slots, e.g., Slot 0
and Slot 1.
4. Write the address of the first value, minus 1, to the configuration register of the first slot in the
sequence. See Table SA-1.
Write the value 252 to register 655. The contents of register 253 will be replicated in register
687, and the contents of register 254 will be replicated automatically in register 688.
5. Write the address of the second value, minus 1, to the configuration register of the second slot
in the sequence. See Table SA-1.
Write the value 41 to register 656. The contents of register 42 will be replicated in register 689.
Additionally, the contents of register 43 will be replicated automatically in register 690, and
register 690 will be read automatically. The host program must ignore the value from register
690.
6. Continue specifying register pairs in consecutive slots until all required values been
configured.
To configure a slot address sequence of Slot Type 2:
1. Determine the process variables that the read command will return, and the order in which
they will be returned. See the Integer Codes list in the Modbus Interface Tool for information
on process variables that can be assigned to slot addresses.
For example, you might want to read volume flow rate and volume total.
2. Identify the integer codes for the process variables.
The integer code for volume flow rate is 5; the integer code for volume total is 6.
3. Determine the slots to be used in the slot address sequence. Each value that the read command
will return requires a separate slot.
To read volume flow rate and volume total, you need two consecutive slots, e.g., Slot 2 and
Slot 3.
4. Write the integer code of the first process variable to the configuration register of the first slot
in the sequence. See Table SA-1.
Write the value 5 to register 753. A floating-point value representing volume flow rate will be
stored in registers 787–788.
Micro Motion® Modbus Interface Tool3
Slots and Slot Address Sequences
5. Write the address of the second value to the configuration register of the second slot in the
sequence. See Table SA-1.
Write the value 6 to register 754. A floating-point value representing volume total will be
stored in registers 789–790.
6. Continue specifying integer codes in consecutive slots until all required values been
configured.
SA 3Reading slot address sequences
Refer to Table SA-1 and issue a read command that identifies the first value register in the sequence
and the number of registers to be read.
Note: When reading a slot address sequence, be sure to specify the value register pairs, not the
configuration registers, and be sure to process or ignore the value in the second register of the value
register pair, as appropriate.
SA 4Long integers in slot address sequences
To include a long integer value in a slot address sequence, configure all registers that contain the long
integer value. Be sure to add them to the slot address sequence in the order you want to read them.
When reading the slot address sequence, the host program must be able to interpret and concatenate
the returned values as required.
SA 5Binary (double-precision) values in slot address sequences
Several process variable codes are used in pairs to return double-precision values. These pairs include:
•34 and 35
•36 and 37
•38 and 39
•40 and 41
•42 and 43
•44 and 45
– used to return mass total
– used to return volume total
– used to return temperature-corrected volume total
– used to return standard volume total
– used to return net mass total
– used to return net volume total
To include a double-precision value in a slot address sequence, two slots are required. Configure the
first slot for the first process variable code, and configure the second slot for the second process
variable code. For example, to return mass total as a double-precision value, write 34 to the
configuration register of the first slot, and write 35 to the configuration register of the second slot.
When you read the first value register pair, the first register will contain Word 0 and the second
register will contain Word 1. When you read the second value register pair, the first register will
contain Word 2 and the second register will contain Word 3. The returned values are in a special,
non-standard, 8-byte floating point format.
Note: For MVD Direct Connect or Series 1000, Series 2000, or Series 3000 transmitters, byte order in
floating-point registers is configurable. Binary totals are not affected by byte order.
4Micro Motion® Modbus Interface Tool
Slots and Slot Address Sequences
MWor d 1 65536×()Word2+()65536×[]Word3+=
TotalFlowM 2
P47–()
×=
M30140 65536×()53586+()65536×[]0+=
M1.2945383
14
×10=
To t a l F low1.294538314×102
27 47–()
×=
To t a l F low1.2945383
14
×102
20–()
×=
To t a l F low1.2945383
14
×109.53674327–×10×=
To t a l F low123 456 789.125,,=
To convert the binary code to the total value, follow the steps below.
1. Calculate M:
2. Set P = Word 0.
3. Calculate as follows:
4. If you are reading mass total (codes 34 and 35), this value represents mass total in grams. If
you are reading volume total (codes 36 and 37), this value represents volume total in cubic
centimeters.
Note: Both M and P are twos complement notation. If you are working with negative values (i.e.,
reverse flow), adjust this method as required.
ExampleReading binary totals
Reading the slot addresses returns the following values:
•Word 0 = 001B (decimal value: 27)
•Word 1 = 75BC (decimal value: 30140)
•Word 2 = D152 (decimal value: 53586)
•Word 3 = 0000 (decimal value: 0)
Calculate M:
P = 27.
Calculate total flow:
Micro Motion® Modbus Interface Tool5
Slots and Slot Address Sequences
SA 6Slot address examples
Example 1Slot address sequence – Slot Type 1 (addresses)
Several times per day, the operator needs to read the following:
•Floating-point volume flow rate
•Volume flow unit
•Floating-point process density
•Density unit
The volume flow unit is gal/min (integer code 16). The density unit is
3
g/cm
(integer code 91).
Configure a slot address sequence so the operator can read the
required values by issuing a single read command. Slots 0 through 3
will be used.
1. Write the integer value 252 to register 655. The value represents
register pair 253–254, which stores the volume flow rate.
2. Write the integer value 41 to register 656. The value represents
register pair 42–43. Register 42 stores the volume flow unit. You
must ignore the value stored in register 43.
3. Write the integer value 248 to register 657. The value represents
register pair 249–250, which stores the process density.
4. Write the integer value 39 to register 658. The value represents
register pair 40–41. Register 40 stores the density unit. You must
ignore the value stored in register 41.
If the operator reads register pairs 687–688 through 693–694, the
transmitter returns a series of values similar to the following:
23.03816 61.09191 33
(Volume flow
rate)
(Volume flow unit plus
next register)
(Process
density)
(Density unit plus next
register)
6Micro Motion® Modbus Interface Tool
Slots and Slot Address Sequences
Example 2Slot address sequence – Slot Type 2 (process variables)
Several times per day, the operator needs to read the following:
•Temperature in degrees Fahrenheit
•Volume flow rate in gallons/minute
•Drive gain in milliamps
•Left pickoff voltage in millivolts
•Right pickoff voltage in millivolts
Configure a slot address sequence so the operator can read the
required values by issuing a single read command. Slots 4 through 8
will be used.
1. Write the integer value 1 to register 755. The value represents the
integer code for temperature.
2. Write the integer value 5 to register 756. The value represents the
integer code for volume flow.
3. Write the integer value 47 to register 757. The value represents the
integer code for drive gain.
4. Write the integer 49 to register 758. The value represents the
integer codes for left pickoff voltage.
5. Write the integer code 50 to register 759. The value represents the
integer code for the right pickoff voltage.
If the operator reads register pairs 791–792 to 799–800, the transmitter
returns a series of values similar to the following:
60.0923.0387.00917087.0517087.02
(Temperature)(Volume
flow rate)
(Drive gain)(Left pickoff)(Right pickoff)
Each of these values is returned using the unit that has been
configured for the process variable. This example assumes that the
required units (as listed above) have already been configured.