Set an iSIC to Output Data to Modbus Slave

NexSens iSIC and SDL500 data loggers can be setup to send data to a Modbus slave device after logging data to the internal flash memory. This is a “hybrid” data logger/Modbus device mode. The iSIC or SDL500 may be set in this mode by sending a command through the control menu:

1. Enable the iSIC Command tab in the iSIC Setup menu:

http://www.nexsens.com/knowledge-base/software/ichart/enable-isic-command-tab.htm

2. Go to Advanced | iSIC | iSIC to access the iSIC Setup menu.

3. Enter the appropriate communication parameters (PC COM port, Connection type, iSIC/SDL Address) and click Connect.

4. Click the General tab. Confirm that the connection was successful by viewing the information in the Status group box. If any fields display “???”, go back to Step 3 and attempt to reconnect.

5. Confirm that the iSIC or SDL500 is set to Data logger mode. If it is not, check the box next to Change iSIC mode and select Data logger from the drop-down list. Click Apply to submit the change.

6. Click the iSIC Command tab. Select GSET_MODBUSOUTPUTCFG from the Command drop-down list.

7. Enter the appropriate argument to configure the iSIC or SDL500 and click Send. Arguments are entered in the format [0] [1] [2] [3] [4..5] [6] [7] [8] [9] [10..11] [12]. See the Appendix at the end of this article for an explanation of the argument fields 0-12.

Two examples are shown below:

Example 1: Query current Modbus settings

Command: GSET_MODBUSOUTPUTCFG

Argument: none (empty)

Response

Send: 21 01 64 06 ad 00 e8

Receive: 21 64 01 07 06 0e 00 00 00 01 00 00 02 06 03 00 32 00 02 00 40

Example 2: Set Modbus output configuration (to Modbus RTU, address 1, starting register 0000, 16-bit unsigned data type, RS485 port, 9600 baud)

Command: GSET_MODBUSOUTPUTCFG

Argument: 1 0 0 1 0x0000 0 6 3 0 0x0064 3 0

Response

Send: 21 01 64 0f ad 0e 01 00 00 01 00 00 00 06 03 00 64 00 03 00 5f

01 – Enable Modbus output

00 – Modbus RTU

00 – Do NOT write timestamp to Modbus slave device

01 – Modbus address 1

00 00 – Starting Modbus register 0000

00 – Data type 16-bit unsigned

06 – Port RS485

03 – Baud 9600

00 – Frame 1 start bit, 8 data bit, 1 stop bit, no parity

64 00 – Timeout 100 = 1000ms = 1second

03 – Retries 3

00 – Do NOT skip bad data

Receive: 21 64 01 10 06 0e 01 00 00 01 00 00 00 06 03 00 64 00 04 00 04

 

 

Appendix – Argument Fields

[0] – Active flag

• 0: Set Modbus output  OFF
• 1: Set Modbus output  ON

[1] – Modbus type

• 0: RTU
• 1: ASCII

[2] – Output timestamp

• 0: do NOT output sample timestamp
• 1: Output sample timestamp (UNIX Epox) in the first 2 register

[3] – Modbus address

[4..5] – Starting Modbus register (little endian)

[6] – Data type

• 0: 16-bit unsigned
• 1: 32-bit unsigned (big endian)
• 2: 32-bit IEEE 754 float (big endian)
• 3: 32-bit unsigned (little endian)
• 4: 32-bit IEEE 754 float (little endian)

[7] – iSIC port (0 to 5 for RS232 port 0 to RS232 port 5; 6 for RS485)

• 0: RS-232 port 0 (MS8 connector)
• 1: RS-232 port 1 (Pins 5 and 6 [P1.Rx, P1.Tx] on iSIC Digital Terminal)
• 2: RS-232 port 2 (Pins 8 and 9 [P2.Rx, P2.Tx] on iSIC Digital Terminal)
• 3: RS-232 port 3 (Requires digital expansion)
• 4: RS-232 port 4 (Requires digital expansion)
• 5: RS-232 port 5 (Requires digital expansion)
• 6: RS-485 port  (Pins 11 and 12 [P3.Rx, P3.Tx] on iSIC Digital Terminal)

[8] – Baud rate

• 0: 1200 baud
• 1: 2400 baud
• 2: 4800 baud
• 3: 9600 baud
• 4: 19200 baud
• 5: 38400 baud
• 6: 57600 baud
• 7: 115200 baud

[9] – Frame

• 0: N81 – 1 start bit, 8 data bit, 1 stop bit, no parity
• 1: E71 – 1 start bit, 7 data bit, 1 stop bit, even parity
• 2: E81 – 1 start bit, 8 data bit, 1 stop bit, even parity
• 3: O81 – 1 start bit, 8 data bit, 1 stop bit, odd parity

[10..11] – Timeout in 10ms  (little endian), i.e. 1 = 10ms

[12] – Number of retries

[13] – Skip bad data flag

• 0: do NOT skip bad data – write bad data to Modbus slave device
• 1: skip bad data – do not write bad data to Modbus slave device

 

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