Function Codes 16 (10H) - Preset Multiple Registers - Honeywell HC900 User Manual

4.10 Function Codes 16 (10h) - Preset Multiple Registers

Description
Presets values into a sequence of holding registers (also refered to as 4X references). The HC900 does not
support Broadcast. The register assignments specified in Section 6 with an access type "W", can be written
to via Function Code 16 (10h).
Writing to half of a digital variable will be accepted. A non-zero write to either register will result in a
floating point 1 to be written to the variable. Writing a zero to either register will result in the variable being
set to 0.
Query
The query message specifies the register references to be preset. Registers are addressed starting at zero:
Register 1 is addressed as 0.
Example: Preset Rack #1, Variable #1 (address 18C0h) to 100.0 in the controller at slave address 1.
Slave
Address (00
for TCP)
TCP 00
Example
RTU 01
Example
Response
The normal response returns the slave address, function code, starting address and the quantity of registers
preset.
The floating point values require two consecutive addresses. A request to preset a single floating point value
must be for two addresses. The byte order of the floating point number is determined by the setting of the
byte swap configuration value. In this example the byte swap order is FP B. Refer to subsection 1.3. The
first 16 bits of the response contain the IEEE MSB of the float value. The second 16 bits of the response
contain the IEEE LSB of the float value. The Byte order is configurable See Subsection 1.3. If the master
station requests only one address at an address of a floating point value the slave will respond with an
illegal data address exception code (See Section 5).
Example: Response from presetting Rack #1, Variable #1 (address 18C0h) to 100.0 from the controller.
Address (00
TCP Example
RTU Example
Revision 13
April 2017
Query message format for function code 16 (10h)
Function Start Start
Code Address Address
High Low
10 18 C0
10 18 C0
Response message format for function code 16 (10h)
Slave Function
Code Address
for TCP)
00 10
01 10
HC900 Process Controller Communications User Guide
Modbus/TCP & Modbus RTU Function Codes
Function Codes 16 (10h) - Preset Multiple Registers
Number Number
Addresses Addresses
High Low
00 02
00 02
Start Start Number
Address Addresses
High Low High
18 C0 00
18 C0 00
Byte Data CRC
Count (RTU)
04 42 C8 00 00
04 42 C8 00 00 CRC
Number CRC CRC
Addresses (RTU) (RTU)
Low
02
02 CRC CRC
CRC
(RTU)
CRC
37