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Configure Comms Port

When configuring the comms port, you will need to specify :


  • Serial or Ethernet Connection
  • COM Port
  • Baud Rate
  • Number of Data Bits
  • Parity
  • Stop Bits
  • Flow Control method

 

Configure Modbus Device

When creating a new device, you will need to specify :


  • A name for the device
  • The Modbus address of the device
  • An optional millisecond delay before transmitting data from the device
  • The mode of the device, either RTU or ASCII
  • Optionally to reverse the CRC in RTU mode (some Modbus devices implement the CRC the wrong way round !)

 

Configure Poll Block

When creating a new data block, you will need to specify :


  • A name for the block
  • The Modbus slave device the block is attached to
  • The start address of the data block
  • The type of data to emulate
  • The number of data words/bits in the block (from 1-10000)

 

 

Configure Scripts

When creating a new script,
you will need to specify :


  • A name for the script
  • The type of script :
  •     Data change
  •     Timer
  •     Manual

 

 

Timer Scripts

When creating a timer script, you will need to specify :


  • The period of the timer (in ms)
  • Whether the timer is a one-shot or periodic
  • Whether to auto-start the script on loading the configuration file

 

Data Change Scripts

When creating a data change script, you will need to specify :


  • The name of the poll block you wish to monitor
  • The data address within the poll block whose value you wish to monitor
  • The value you want to monitor against
  • The condition you wish to check

 

Example Script Text

 

When writing the script, you use a language syntax similar to machine code. There is one instruction per line and it consists of an opcode following by one or two parameters. The list of opcodes are :

OpcodeParam 1 Param 2Comment
INC<tag>   Add 1 to the value of P1
DEC<tag>   Sub 1 from the value of P1
TOG<tag>   Toggle the bit value of P1
CLR<tag>   Set P1 to 0
SET<tag> <tag>|<val>Set P1 to P2
ADD<tag> <tag>|<val>Add P2 to P1
SUB<tag> <tag>|<val>Subtract P2 from P1
NEG<tag>   Negate P1
STO<tag>|<val> <tag>Store P1 in P2
JMP<label>   Jump to label
CMP<tag> <tag>|<val>Compare P1 with P2
JE<label>   If equal, jump to label
JNE<label>   If not equal, jump to label
JL<label>   If less, jump to label
JLE<label>   If less or equal, jump to label
JG<label>   If greater, jump to label
JGE<label>   If greater or equal, jump to label
END   Terminate script

Where <tag>|<val> is specified, you can either use a tag or an immediate value.

where :

<tag> = data address in the format <block name>:<address>

    eg BLOCK1:40001

<val> = numeric value

<label> = line label in the format :<label>

eg :HERE

Please note that line labels must appear on a line on there own and not followed by an instruction.

An example clock timer script is :

Script Name : CLOCK
Type : Timer
Periodic with period 1000ms
Script :
   INC BLOCK1:40003
   CMP BLOCK1:40003 60
   JNE DONE
   CLR BLOCK1:40003
   INC BLOCK1:40002
   CMP BLOCK1:40002 60
   JNE DONE
   CLR BLOCK1:40002
   INC BLOCK1:40001
:DONE
   END

Alternatively, this could be done similarly with one timer script and two data change scripts, eg :

Script Name : SEC
Type : Timer
Periodic with period 1000ms
Script :
   INC BLOCK1:40003

Script Name : MIN
Type : Data Change
Tag : BLOCK1:40003
Condition : = 60
Script :
   INC BLOCK1:40002
   CLR BLOCK1:40003

Script Name : HOUR
Type : Data Change
Tag : BLOCK1:40002
Condition : = 60
Script :
   INC BLOCK1:40001
   CLR BLOCK1:40002

These example scripts are assuming you have already created a poll block called BLOCK1 of type 3 (holding registers) starting at address 40001 with at least 3 data words in the poll block.

To test these scripts (after entering them in the program of course !), click on either CLOCK or SEC in the script list then click the Run button. If you then change view to see BLOCK1 and change the data format to signed integer, you should see the first three data values simulating a clock, incrementing in value once per second. You can quickly check the second and minute rollovers by clicking on address 40003 and/or 40002 and setting it's value to, say, 55 to speed things up a bit.

If you have ideas for further opcodes or require clarification on any point of writing scripts, please contact me.



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Copyright 2006 Jon Welch
Last modified: 12-09-2011