Appendix B Exception Responses - Honeywell Notifier MODBUS-GW Installation And Operation Manual

If a Modbus master device sends an invalid command or attempts to read an invalid holding register, an exception response is generated.
The exception response follows the standard packet format. The high order bit of the function code in an exception response is 1. The
data field of an exception response contains the exception error code.
ported and the possible causes.
Exception Code
44

Appendix B Exception Responses

Table B.1 Exception Codes
• Protocol Identifier in Modbus packet does not match
0x01
Modbus protocol. Protocol Identifier in Modbus should
always be "0".
• Function code sent by the client is not supported by the
MODBUS-GW or the FACP.
• A Control command was sent to the gateway. Contact
customer service.
• Register address range specified by the client is not
0x02
supported by the FACP.
• Register address range requested is valid but the device
(e.g. Detector, Module, Zone, etc.) is not present in the
specified FACP.
• Analog Value is requested from a register which is not
associated with a 4–20 mA device.
• Number of registers requested exceeds the maximum
0x03
allowed limit. The maximum number of registers that a
client can read at one time is 100. The exception to this is
for analog values where the maximum number of
registers a client can read at one time is 10.
• Invalid Data written to the register when sending
commands.
0x0A Unit ID specified in the request packet is not configured for
monitoring.
0x0B FACP is off line or there is a communication problem on the
panel and/or NFN.
MODBUS-GW Installation and Operation Manual — P/N LS10015-000NF-E:C2 4/30/2019
Table B.1, "Exception Codes"
Conditions
describes the exception codes sup-
Exception Name
Illegal function
Illegal data address
Illegal data value
Gateway path failed
Gateway target failed