Micro Motion Manual: Modbus Interface Tool - Slot and Slot Address Sequences | Micro Motion Manuals & Guides

Micro Motion® Modbus Interface Tool

Slots and Slot Address Sequences

SA 1 Overview

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 1 Slot Type 2

Address of

Slot

0 655 687 688 751 783 784

1 656 689 690 752 785 786

2 657 691 692 753 787 788

3 658 693 694 754 789 790

4 659 695 696 755 791 792

5 660 697 698 756 793 794

6 661 699 700 757 795 796

7 662 701 702 758 797 798

8 663 703 704 759 799 800

9 664 705 706 760 801 802

10 665 707 708 761 803 804

11 666 709 710 762 805 806

12 667 711 712 763 807 808

13 668 713 714 764 809 810

14 669 715 716 765 811 812

15 670 717 718 766 813 814

16 671 719 720 767 815 816

17 672 721 722 768 817 818

18 673 723 724 769 819 820

19 674 725 726 770 821 822

20 675 727 728 771 823 824

21 676 729 730 772 825 826

22 677 731 732 773 827 828

23 678 733 734 774 829 830

24 679 735 736 775 831 832

25 680 737 738 776 833 834

26 681 739 740 777 835 836

27 682 741 742 778 837 838

28 683 743 744 779 839 840

29 684 745 746 780 841 842

30 685 747 748 781 843 844

31 686 749 750 782 845 846

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.

2 Micro Motion® Modbus Interface Tool

Slots and Slot Address Sequences

SA 2 Configuring 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 Tool 3