FAQ
Q: How does Modbus Gateway work in iSMA-B-XX-IP modules?
In iSMA-B modules with IP, Modbus Gateway service is always enabled. Regardless of the protocol selected in the device (Modbus / BACnet), the Modbus TCP to Modbus RTU converter is still working. The frame received on the Modbus TCP port is checked for compliance of the Modbus address with the device address. If the addresses are different, the frame is translated into Modbus RTU and transferred to the RS485 bus.
Q: Digital outputs or analog outputs take a value other than the set value. Why?
iSMA modules have a watchdog chip that watches correctly received protocol frames. If the device has not received a valid frame within a certain time, the watchdog resets the outputs to their default values.
Q: Can iSMA-B-XX-IP module respond to Modbus queries of the master controller via RS-485 buses?
iSMA-B-XX-IP modules communicate with the supervisory controller only via Ethernet. The RS-485 port in iSMA-B-XX-IP devices only works with Modbus Gateway functionality.
Q: Does Gateway function in iSMA-B-XX-IP modules also work for BACnet protocol?
No, iSMA-B-XX-IP devices only have a built-in Modbus gateway.
Q: Does iSMA-B-XX-IP module have to be set to work with the Modbus protocol if the Gateway function is to work properly?
No, the module does not need to be set to work with the Modbus protocol. It can work in the BACnet mode and simultaneously send Modbus registers to slaves on the RS485 bus.
Q: How does Watchdog work in iSMA-B-XX modules?
If the correct communication frame was not sent to iSMA device in the time set in the "Watchdog" slot, the device will activate all its outputs to the "default state" value.
Q: How to disable Watchdog in iSMA-B-XX modules?
To disable the Watchdog system, enter the value 0 in iSMA Configurator in the "Watchdog time" slot or change it using the appropriate Modbus register or BACnet object.
Q: What time for the watchdog should be set?
The response time should be longer than the slowest time of polling points of the device or pinging the device by the superior controller.
Q: How to restore iSMA-B-XX module to factory settings?
Connect to the module using iSMA Configurator, right-click on the device name (in the tree on the left) and select the "Default settings" option. You can also restore the factory settings with the 6 "Dip switch".
Q: How to restore iSMA-B-XX module to factory settings using 6 "Dip switch"?
Disconnect the module power supply,
set 6 "Dip switch" to ON position,
turn on the module power supply,
turn 6 "Dip switch" to OFF position.
Q: What are the supported Modbus function for the reading and writing on a iSMA-B-XXX
MIX and MINI modules supports Modbus functions listed below:
Read:
01: Coils (FC=01)
02: Discrete Inputs (FC=02)
03: Multiple Holding Registers (FC=03)
04: Input Registers (FC=04)
0x2B : to read the VENDOR_NAME,MODEL_NAME, FW_VERSION, HOMEPAGE
Write:
05: Write Single Coil
06: Write Single Holding Register
15: Write Multiple Coils
16 : Write Multiple Holding Registers
0x17: Read/Write Multiple registers