Utilized Register Block List (URBL). ABB POWER LEADER™ ModBus® Monitor

POWER LEADER Modbus Monitor

Chapter 7 – Advanced Configuration

Add Register

Click Add Register to enter a new register:

Modify Register

To modify an existing register, select it from the register map list and click Modify to change any of its attributes.

The dialog box to change an existing register is the same as to add a new register, but instead of coming up blank, the current values for each register attribute are displayed. Make any appropriate changes and click OK.

Delete Register

To delete a register, select it from the register map list and click Delete Register. The register will be removed from the list and also from any custom screens on which it has been displayed.

Figure 48. Monitor Configuration Tool: Add Register dialog box.

Enter the register mnemonic, the register type, the numeric register address. Select the register format and the scaling factor from the pull-down lists. The table below describes each field in more detail. Refer to the device’s documentation for more information.

Register

Mnemonic

Register

Type

Register

Address

Register

Format

Scaling

Factor

Text string, no spaces or special characters.

R0 - coil

R1 - contact

R3 - input

R4 - holding

See device documentation for details.

Decimal integer only.

Range 0 - 9999 for standard addressing.

Range 0 - 65535 for extended addressing.

See device documentation for correct range.

See Appendix C for more information. The Modbus Monitor does not support any Register Formats not shown in this pulldown list.

Default = 1. Select other scaling factors from pulldown list.

Register is multiplied by this value prior to being displayed on the Monitor’s screen.

Click OK when the register information is complete. The register will now appear in the register map list.

Utilized Register Block List (URBL)

Because of the nature of Modbus RTU communications, where obtaining a register value requires the master to query the slave and the slave to send a reply, when you wish to obtain several register values it is more efficient to request them all together in a single block. The master will only have to send one request and the slave will only have to send one reply, even though the reply contains additional data.

The Modbus Monitor supports up to 10 blocks of registers for each register type. A block may contain from 1 to 125 registers. The register addresses must be contiguous; that is to say, no holes or skipped addresses are permitted. If you wanted to obtain data from registers at addresses 1000, 1015, 1040 and 1042, you would create a single block of registers starting at 1000 and ending at 1042 by defining each register in between, without skipping any, even those of no interest. The only exception to this rule is that some registers, such as floating point registers, may occupy multiple addresses; you are not required to enter each of these addresses, only the first one. This should be evident from the device’s register map, where the address will probably be listed as (for example), 1000-1003.

The idea of register blocks becomes important when you attempt to customize screens of data, because the

Modbus Monitor will look at the register fields for display on a screen and will only request up to 10 register blocks. If all the registers you are attempting to display can be retrieved by requesting 10 or fewer register blocks, the screen will be displayed correctly. If more than 10 register blocks must be requested to

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