Rockwell Automation 2706-P42_P43_P44_P72_P74_P92_P94 InView Marquee Message Display User Manual - Manual (Page 105)

Publication 2706-UM016D-EN-P - March 2006
InView Protocol 4-39
The normal response to a function 03 query is to echo the address,
function code, starting address and the data for the registers that were
requested.
Response for Requesting Message Queue Data
Read Variables in a Display using a Modbus ASCII 03 frame
This function allows the ability to read variable data stored in a
display. A maximum of 100 registers can be read since there is a
maximum of 100 registers of data. Below is an example of the request
for registers 40002 through 40004 in display address 020.
Transmission:
Query for Requesting Variable Data
Response:
The addressed slave responds with its address and the function code,
followed by the information field. The information field contains 2
bytes describing the quantity of data bytes to be returned. The
contents of the registers requested (DATA) are two bytes each, with
the binary content right justified within each pair of characters. Below
shows the response to query for registers 40002 through 40004 having
the decimal contents of 44, 63, and 1 respectively.
Beginning
of Frame ADDR FUNC BYTE
COUNT DATA
OUTPUT
REG H.O.
0066 DATA
OUTPUT
REG L.O.
0066 DATA
OUTPUT
REG H.O.
0067 DATA
OUTPUT
REG L.O.
0067
: 0A 03 06 00 04 00 06
DATA
OUTPUT
REG H.O.
0068 DATA
OUTPUT
REG L.O.
0068 LRC EOF Ready to
rec. resp
00 0B D8 CR LF
Beginning
of Frame ADDR FUNC H.O.
ADDR L.O.
ADDR DATA Number
of register to
read LRC
Error EOF Ready to
rec. resp
: 14 03 00 01 0003 E5 CR LF