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MiriAD 2000 Modules |
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Radio Modems |
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Applications |
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Ladder Diagram Programming Interface
The MiriAD 2000 units have a Ladder Diagram interface to allow programmable logic functions to be performed on the internal variables and field I/O variables (i.e. digital and analogue inputs and outputs). This allows the MiriAD 2000 units to be used in similar applications to devices commonly referred to as PLCs (i.e. Programmable Logic Controllers). The choice of the familiar Ladder Diagram language as an interface has been made to provide an easy to understand graphical interface, consistent with the graphical methods already used in the MiriMap2000+ Configuration Software.
The following Ladder Diagram Functions are supported.
Boolean Logic
- Normally Closed Contact
- Positive Transition Contact
- Negative Transition Contact
- Any Transition Contact
- Output Coil
- Not Output Coil
- Set Output Coil
- Reset Output Coil
Timers and Counters Function Block Descriptions
- Counter Up (CTU)
- Counter Down (CTD)
- Counter Up Down (CTUD)
- Timer Pulse (TP)
- Timer On-Delay (TON)
- Timer Off-Delay (TOFF)
- Timer Accumulating (TACC)
Data Manipulation Function Block Descriptions
- Greater Than (GT)
- Less Than (LT)
- Equal To (EQ)
- Bit Shift Left (SHL)
- Bit Shift Right (SHR)
- Rotate Left (ROTL)
- Rotate Right (ROTR)
- Decrement
- Increment
Arithmetic Function Block Descriptions
- Add (ADD)
- Subtract (SUB)
- Multiply (MUL)
- Divide (DIV)
Special Function Block Descriptions
- Change Detect
- High Speed Counter for DIN1 and DIN2 (High Speed DIN2 only available on MiriAD 2002)
- High Speed Rate Calculation for DIN1 and DIN2 (High Speed DIN2 only available on MiriAD 2002)
- Log
- Moving Average
- Parcel
- Rate Calculation
- Scale
- Shaft Encoder Interface
The physical memory in the MiriAD 2000 is assigned as 16 bit word memory locations. In the IEC standard IEC1131-3 Programmable controllers Part 3: Programming languages (the MiriMap2000+ software package has been based on this standard) several elementary data types are defined (refer to Table 10 "Elementary data types" in the IEC1131-3 standard for further details). All memory in the 64k word user memory of the MiriAD 2000 can be addressed as 3 of these elementary types:
- WORD - 16 bits, (IEC keyword INT).
- LONG - 32 bits, (IEC keyword DINT).
- DLONG - 64 bits, (IEC keyword LINT).
Since the MiriAD 2000 variable addresses are a direct representation of single element variables the special symbol of the percent sign "%" is used to designate this. All the MiriAD 2000 variables (including the physical variables since they are mapped internally to a memory variable address) are in memory so have the prefix M for Memory added. The next prefix added is W, D, L, depending on whether the memory is addressed as a word, double word or long word, respectively. For further details on this location and size prefix detail refer to Table 15 - "Location and size prefix features for directly represented variables" in the IEC1131-3 standard.