IntelliSAW IRM-48 Reader
Installation Manual
Page 21 of 28
IRM-48 Reader
910.00371.0001
6
S
YSTEM
I
NTEGRATION
The IRM-48 Reader has one RS485 slave communication connection. The Reader can be
connected to a CAM-4 unit or an existing SCADA, DCS, or historian system. All IRM-48 readers
are slave devices polled by either a Master CAM-4 unit or SCADA system.
The following Modbus information is for Reader Firmware rev.1123 or higher.
For legacy Modbus Register data, please contact IntellISAW support.
6.1
M
ODBUS
C
OMMANDS
The Reader treats holding and input registers identically; however HOLDING registers are the
preferred approach. Modbus-RTU payloads always begin with the address and a function code
(FC). The Reader supports the following Modbus function codes, as shown in the following
table:
Command
FC
Description
2
Function code required by CiTect
MBF_READHOLDING
3
Fetch up to 81 of 256 defined registers
MBF_READINPUT
4
Exactly duplicates the MBF_READHOLDING command with
the same registers
MBF_PRESETSINGLE
6
Set a single register
– do not use in reserved registers
MBF_DIAGNOSTICS
7
Sub-functions supported are 1, 4, 10-14
MBF_FETCH_CEC
11
Return 0x0000 if not busy, 0xFFFF if busy
MBF_PRESETMULTIPLE
16
Set up to registers
MBF_RESET_COMM
19
Reset reader processor if successful.
MBF_RESET_COMM_ISR
7E
<address> <7E> <AA> <55> <crc1> <crc2> resets reader
XMS_XMESSAGE_FC
7F
The remainder of the payload contains a native command.
Modbus-RTU payloads obey the MODICON standard except for special function codes, 7E and
7F. For the 0x7F function code, the payload begins with address and 0x7F followed by an
IntelliSAW native protocol command payload.
The MBF_RESET_COMM_ISR command is a special sequence that reboots the processor
from within the serial receive interrupt service routine, regardless of protocol, when it is detected
from a serial line idle condition.
The MBF_RESET_COMM_ISR command must be properly formatted and successfully parsed.
This special sequence offers a means of resetting a reader that is otherwise externally
unresponsive.
