SECTION 3
CIM PROTOCOL
PM055 Rev 2 00/08/31
Thomson Technology
52
It is also recommended to follow up with a Display Valid Flag read to
insure the operation was successful before proceeding. The CIM does
attempt multiple operations in the case of a bad packet. However, if the
Display Valid Flag is not valid after 900ms a retry should be performed.
5.
Read Holding Registers (Type 3)
The read holding register request is used for read data from the controller.
Numeric values are shown in hexidecimal.
5.1.
Read Holding Registers Request
Field addressing is done with the following format:
ss 03
aaaa pppp cccc
ss
MEC 20 ID (00 to FF)
aaaa
Starting register (4aaaa)
pppp
Register count
cccc
CRC-16 (see
CRC Calculation
)
5.2.
Read Holding Registers Response
ss 03 bb rrrr . . . . rrrr
cccc
ss
MEC 20 ID (00 to FF)
bb
Response Byte count (Register count x 2)
rrrr
Register data (16 bit data)
cccc
CRC-16 (see
CRC Calculation
)
5.3.
Example: Read Registers 200 To 201
SEND:
ss 03
0200 0002 cccc
ss
MEC ID (00 to FF)
