Appendix B – Modbus Protocol
NMBA-01 Installation and Start-up Guide
B-15
16 (10 Hex) Preset
Multiple Regs
Presets values into a sequence of holding registers (4X references).
When broadcast, the function presets the same register references in
all attached slaves.
The NMBA-01 allows one or multiple registers to be written at one time
using one Preset Multiple Regs function. Only registers within one
group can be written at one time. If a write to one of the registers fails,
the module will try to write to other registers, but the response will con-
tain a corresponding exception message.
Query
The query message specifies the register references to be preset.
Registers are addressed starting at zero: register 1 is addressed as 0.
The requested preset values are specified in the query data field. The
NMBA-01 uses 16-bit values. Data is packed as two bytes per register.
Here is an example of a request to preset one register starting at
40002 to 00 0A in slave device 17:
Figure B-9 Preset Multiple Registers - Query
QUERY
Field Name
Example
(Hex)
Slave Address
11
Function
10
Starting Address Hi
00
Starting Address Lo
01
No. of Registers Hi
00
No. of Registers Lo
01
Byte Count
02
Data Hi
00
Data Lo
0A
Error Check CRC
CRC (16-Bits)
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