User's Manual

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Slave ID Map Example
Suppose you have two ASCII slave devices on port 1 assigned to slave IDs 3 and 5. The MGate will
automatically create a virtual ID range for port 1, which you will need to modify. If slave IDs 3 and 5 are
already in use by TCP slaves, the virtual ID range should be set to IDs that are not in use, such as 20
through 22. In that case, you would specify a slave ID offset of -17, since that is the difference between
the virtual ID range and the actual slave IDs. The formula is as follows:
(Real Slave ID) - (Virtual Slave ID) = (Slave ID Offset)
3 - 20 = -17
With the slave ID map configured, a master that wants information from one of the ASCII slaves would
address the request to slave ID 20 or 22. The MGate would identify that the request was addressed to a
virtual slave ID in the slave ID map. The MGate would then forward the request to port 1, applying the
-17 offset to obtain the actual ID of the desired device.
Priority Control
Priority control is designed for requests that are sent to Modbus RTU/ASCII slaves. Since Modbus
RTU/ASCII slaves cannot handle multiple requests, the Modbus gateway must send each request
individually and wait for the response before sending the next request. As requests stack up, the
response time can suffer. This can cause problems for certain critical requests that require an immediate
response.
With priority control, you can specify that certain requests are sent to the front of the queue for more
immediate response times. Priority requests can be specified by master (IP address or serial port), TCP
port, or command type (slave ID, function code, or data). When the Modbus gateway identifies a priority
request, the request will immediately be placed at the front of the queue.
Parameter Value Default
Specified TCP port Enable
Disable
Disable
TCP Port 1024-65535 7502
Specified Master Enable
Disable
Disable
Add Master Serial Port (RTU/ASCII Master)
IP Address (TCP Master)
Serial Port
(RTU/ASCII master)
Serial Port 1 - 2 null
IP Address Max 40 characters null
Specified request Enable
Disable
Disable
Slave ID 0 - 255 null
Function code 0 - 255 null
Data (RTU Format in Hex) Max 254 bytes
Advanced Settings
Parameter Value Default
Initial delay 0 ~ 30000 ms 0
Modbus TCP exception Enable
Disable
Disable
Modbus TCP listen port 0 ~ 65535 502
Modbus TCP response
timeout
10 ~ 120000 ms 1000
Slave ID 1 ~ 255 247