Power Measurement 3300 ACM User Manual

3300 ACM Installation and Operation Manual Power Measurement Ltd.
Appendix G: Serial Communications Protocol G-5
Figure G-1 Read Registers Packet
3 PACKET COMMUNICATIONS
This section details all packet communications into and out of
the model 3300 ACM power meter. There are only two
different packet types: one for reading the registers and the
other for writing them.
Section 3.1 discusses the command packet to read the
registers, and the response packet issued by the meter.
Section 3.2 discusses the command packet to write data to the
registers, and the acknowledgement packet issued by the
meter.
3.1 READ REGISTERS PACKET
This request packet is sent by the Master Station (the PC) to
request that the 3300 ACM respond with all valid registers
within the range given by Start register and End register.
Typically no password is required to read the registers. In this
case any number may be placed in the password location of
the packet. There are, however, two cases where the correct
password is required.
1) To read a protected register. Presently the only protected
register is the register where the meter password is held.
2) If the PROTECTED READ ONLY register (address 0A10
hex) has been set. In this case the password must be
correct to read any register.
Only valid registers will be sent in the response packet.
Registers for which the meter is not equipped, or do not exist
for a given voltage mode will not be sent.
NOTES:
1. Registers are 4 bytes with 1 byte register address LSB field and 3 bytes data field.
2. A register address value of 0 indicates a page change to the page given in the data field.
3. The maximum number of registers in a response packet is 61. If there are more valid registers in the requested range the last register
will be change to page FF.
READ REGISTER PACKET
(Master to 3300 ACM)
14 (1 byte)
FD (1 byte)
83 (Read Registers command) (1 byte)
Length (1 byte)
Master address (2 bytes)
3300 address (2 bytes)
Password (2 bytes)
Start Register requested (2 bytes)
End Register requested (2 bytes)
LRC Checksum (1 byte)
READ RESPONSE PACKET
(3300 ACM to Master)
27 (1 byte)
FD (1 byte)
83 (Read Registers command) (1 byte)
Length (1 byte)
3300 address (2 bytes)
Master address (2 bytes)
Device Type (2 bytes)
Number of Registers sent (2 bytes)
1st Register in Range (4 bytes)
2nd Register in Range (4 bytes)
... ...
... ...
LRC Checksum (1 byte)
Courtesy of NationalSwitchgear.com

Power Measurement 3300 ACM Specifications

General

Brand	Power Measurement
Model	3300 ACM
Category	Measuring Instruments
Language	English