GE Multilin 565 Instruction Manual Download

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FEATURE INFORMATION

6-9

gle Setpoint
This command allows the master to store a single setpoint
into the memory of a slave device. Only two bytes setpoints
can be stored via this function. The slave device response to
this function code is to echo the entire master transmission.

Note: Broadcast mode is allowed with this function code.
When a broadcast transmission is sent by the master (ie.
SLAVE ADDRESS = 0) the selected setpoint will be stored by
all slave devices on the communication link. No response will
be sent from any of the slaves.

Message Format and Example

Request slave 11 to store the value 039E in setpoint address
0087. After the transmission in this example is complete,
setpoints address 0087 will contain the value 039E.

Master Transmission:

HI LO

00 87

03 9E

?? ??

ADDRESS FUNCTION

START

DATA

CRC

CODE

ADDRESS

Slave Response:

HI LO

00 87

03 9E

?? ??

ADDRESS FUNCTION

START

DATA

CRC

CODE

ADDRESS

FUNCTION CODE 07
Modbus Implementation: Read Exception Status
565 Feeder Management Relay Implementation: Read De-
vice Status
This is a function used to quickly read the status of a selected
device. A short message length allows for rapid reading of
status. The status byte returned will have individual bits set to
1 or 0 depending on the status of the slave device.

Note: Broadcast mode is not allowed with this function code.
The master transmission will be ignored by all slaves if
broadcast mode is used with this function code.

Message Format and Example

Request status from slave 11.

Master Transmission:

HI LO

?? ??

ADDRESS FUNCTION

CRC

CODE

Slave Response:

HI LO

?? ??

ADDRESS FUNCTION

DEVICE

CRC

CODE

STATUS

= 01101101

FUNCTION CODE 16
Modbus Implementation: Preset Multiple Registers
565 Feeder Management Relay Implementation: Store Mul-
tiple Setpoints
This function code allows the master to store a group of
setpoints. The maximum number of holding registers that
can be stored in one transmission is 60. Number of holding
registers has to match the total length of required setpoints.
In the other words writing half of a setpoint is not allowed.
Modbus “registers” are 16 bit (two byte) values transmitted
high order byte first. But all 565 Feeder Management Relay
setpoints are not made of two bytes. Some of them are four
bytes long and in that case two consecutive holding register
addresses are used to transmit data of one setpoint. Holding
register with lower address number carries two more signifi-
cant bytes. The slave device response to this function code is
to echo the slave address, function code, starting address,
the number of setpoints loaded, and the CRC.

Note: Broadcast mode is allowed with this function code.
When a broadcast transmission is sent by the master (ie.
SLAVE ADDRESS = 0) the selected setpoint(s) will be stored
by all slave devices on the communication link. No response
will be sent from any of the slaves.

Message Format and Example

Request slave 11 to store the value 000A to setpoint address
0087 and the value 0102 to setpoint address 0088. After the
transmission in this example is complete, 565 Feeder Man-
agement Relay slave 11 will have the following setpoints
information stored:
Address

Data

0087

000A

0088

0102

Master Transmission:

HI LO

00 87

00 02

00 0a

01 02

?? ??

ADDRESS FUNCTION START

SETPOINT

BYTE

DATA

CRC

CODE

ADDRESS

COUNT

Slave Response:

HI LO

00 87

00 02

?? ??

ADDRESS FUNCTION

START

SETPOINT

CRC

CODE

ADDRESS

COUNT

Error Responses

When a 565 Feeder Management Relay detects an error
other than a CRC error, a response will be sent to the master.
The MSbit of the FUNCTION CODE byte will be set to 1 (ie.
the function code sent from the slave will be equal to the
function code sent from the master plus 128). The following
byte will be an exception code indicating the type of error that
occurred. Transmissions received from the master with CRC
errors will be ignored by the 565 Feeder Management Relay.