(Last Update: 15-Jun-2011, MX FAQ0022)

MX FAQ0001
Q: Will it be possible to program the older DL-PLCs with DirectSOFT-MX?
A: No, only the MX-275 and MX-275e are currently programmable with DirectSOFT-MX.

Originally we intended to allow the programming of the older DL-PLCs, but as the design developed we realized by moving to strong data types and structures we were fundamentally changing the way we did some critical things which moved us further and further away from maintaining compatibility with DL-PLCs. So the decision was made to build the best controller and software we could instead of trying to maintain compatibility with DL-PLCs.

MX FAQ0002
Q: Will there be a DirectSOFT6 for the older DL-PLCs?
A: Yes. After MX is rolled out, there are plans to do another major release of DirectSOFT for the older DL-PLCs.

MX FAQ0003 
Q: Why are there no ISG (Initial Stage) instructions?
In the DL-PLCs there is no program modularity and users are therefore forced to modularize their programs with stages and therefore multiple ISGs were needed.  By contrast, MX-PLCs are designed to be modular (Tasks & Programs) with Programs supporting stages. Since each Program can have its own block of 128 stages running independently and the very first stage is the initial one, then the ISG instruction is not needed. This simplifies stages and encourages a better programming practice of having a single well-defined entry point for a sequence.

If multiple parallel sequences are needed in a single program, use the DIVERGE instruction in the first stage or simply set the other stages from the first stage.

In an MX-PLC, Programs should be thought of as individual sequencing operations and each sequencing operation should have one starting point.

MX FAQ0004
Q: Does the MX-CPU have more memory than the DL260?
A: Yes.

Data 34 Kbytes 256 Kbytes
Program 15,872 instruction words 65,536 instruction words

MX FAQ0005
Q: Are the more complex high-level instructions (e.g. network R/W and Math) more efficient that IBoxes in the DL260?
A: Except for MATH, yes. IBoxes are just macros whereas all the complex instructions in MX are native and all of the interlocking to the instruction and device driver are internal. But as for MATH it is still much faster in the MX (e.g. integer MATH in MX is nearly as fast as the simple contact/coil instructions!).

MX FAQ0006
Q: What is the typical scantime of an MX-PLC?
A: Like all things PLC, this is a wide open question. The minimum scan time is about 150 s. Certain modules that tax the DL205 backplane a bit (e.g. CTRIO/CTRIO2) will raise that. With a single CTRIO2 in the base the minimum scan is about 258 s. Boolean instructions, math and boolean stack operations, and most integer math operations are all very fast, generally running at about 50 ns per instruction, or 50 s per K of logic.

More complex instructions, of course, will increase the scan accordingly. Given typical PLC programming the typical scantime will probably be submillisecond to a few milliseconds. So for most users, speed won't be an issue, especially if Stages and modularity mechanisms are utilized as intended.

MX FAQ0007
Q: Will interrupts be supported?
A: Not at this point. We are considering come changes to that in the future, but it is not critical for the MX-PLC given its performance (speed).

MX FAQ0008
Q: Is the serial communication half or full duplex?
A: Full duplex. It is possible to fill the MX base with H2-SERIO-4 modules and run MX Server, Modbus RTU Server, Modbus RTU Client, K-Sequence Server, or even custom protocols on every port simultaneously.

MX FAQ0009
Q: How many Modbus TCP clients (masters) can talk to the MX-275e internal Ethernet port?
A: The MX-275e can maintain 16 connections as a Modbus TCP Server (slave). If the 17th master attempts a TCP connection, the MX-275e would simply reject the connection request.

MX FAQ0010
Q: Will DirectSOFT-MX be free?
A: We have not decided yet. There are many pros and cons we are considering.

MX FAQ0011
Q: Will there be any type of utility (like DNLoader) that the end customer can use to update their PLC without needing a copy of DirectSOFT-MX and without knowing the PLC password?
A: There are plans on having a very elaborate tool for MX that does this. This tool will button up firmware, program, and data into a single encrypted file and basically take an MX-PLC from an unknown state to ready to run.

MX FAQ0012
Q: What kind of program security does MX have?
A: Each code block in an MX-PLCs can be individually configured as Full Access, Read Only, or Locked. When Locked, the block is not even viewable without a password.

MX FAQ0013
Q: Is there a utility that will translate DL230, DL240, DL250(-1) and DL260 projects into MX projects?
A: Currently, no. Try exporting your DL boolean logic STR/AND/OR/OUT coil and with some minor edits to that file you might could get that to import to MX. However, there is no accumulator exposed via user instructions (i.e. no LD/OUT word, no LD LD LD OP type sequences), hence converting a higher level 240 to an MX program would be like converting assembly into C++, with lots of caveats. But the Export/Import could possibly convert 60-80% of the code with contact/coil, rung comments, and element documentation, but it's the last 20-40% that will need a complete rewrite in DirectSOFT-MX. And actually, it will probably be much easier to write the MX version due to the greatly enhanced high level functions.

MX FAQ0014
Q: What communication protocols are supported by MX?
A: The following:


Write your own:

MX FAQ0015
Q: Will current OPC servers for the DL-PLCs also work for the MX-CPU?
A: Yes, using either Modbus or K-sequence drivers. An MX driver for KepDirect is to be announced.

MX FAQ0016
Q: What are the highest values for timers and counters?
A: Timers are all millisecond resolution using 32-bit signed numbers (-2,147,483,648 to +2,147,438,647), thus millisecond resolution for more than 24 days. Counters are also 32-bit signed numbers, hence you can count up to 2,147,438,647 or down to -2,147,438,648.

MX FAQ0017
Q: Are the familiar DL-PLC memory types supported in MX-PLCs?
A: Most DL memory types also exist in an MX-PLC. X, Y, and C are Discrete Input, Discrete Output, and Internal Bits. However, MX element blocks are numbered in decimal, not octal. So, yes, there is an X8 (and an X9).

V memory in MX is a 16-bit unsigned integer, with a range of 0-65,535. Instead of storing 32-bit IEEE real numbers in V memory, or 32-bit integer in V memory, we created two additional memory blocks, R and D, respectively. Each element in the R block is a 32-bit real number. Each element in the D block is a 32-bit signed 2's complement integer number. Both of these blocks also have decimal IDs.

Use V memory when you need integer values 0-65535.
Use D memory when you need a signed integer.
Use R memory when you need real.

The good news is that the MATH instruction can properly handle mixing and matching any of these data types in MX. For instance, this is a valid MATH expression:
(ROUND(SQRT(R0)) + V8) * D3.

Timer/Counter bits and accumulator values are now part of Timer and Counter structures. T0 represents the entire Timer structure for timer T0. Within these structures are various "dot fields," e.g. .Done .Acc .Reset. To know when Timer #0 is done, enter T0.Done. To look at Counter #9's accumulator, enter CT9.Acc. This means that V0 is User V memory, not T0's accumulator like in the DL-PLCs. Also, all of the .Acc accumulators are 32-bit signed integers with a range of -2,147,438,648 to +2,147,438,647.

MX FAQ0018
Q: Is there an instruction list for MX?
A: What follows is a complete instruction list for MX-275/275e CPUs:

Normally Open, Normally Closed, 
Positive Differential, Negative Differential, Inline Inverter, Inline Differential, Delta(Changed) 
Relational Contacts - ALL 6  =   <>   <   <=   >   >= 
Able to compare ANY types of numeric data V7 > R3 Can also be used inside MATH instruction

Alarm Boxes 
ALDEV Deviation Alarm 
ALHILO High/Low Alarm 
ALRATE Rate of Change Alarm 

Assignment Boxes 
INIT Initialize Multiple Elements 
MEMCOPY Copy Memory 
MOVE Move Value 
MOVER Move Range of Values 
REFWRITE Write Value Indirectly 
RSTR Reset Bit Range 
SETNUMR Set Numeric Range 
SETR Set Bit Range 

BCD Boxes 
BCDTO BCD to Integer/Real 
TOBCD Integer/Real to BCD 

Bit Boxes 
DECO Decode to Set Bit 
ENCO Encode Bit Position 
PONOFF Push On/Push Off 
SUMBITS Count # of 1 Bits 

MX/DL Communication Boxes 
DLRX DirectLOGIC Network Read 
DLWX DirectLOGIC Network Write 
PEERLINK Share Data w/PLCs 

Conversion Boxes 
FREQCNT Frequency Counter 
FREQTMR Frequency Timer 
GRAY Gray Code to Integer 
SCALE Scale Value 
SEG Hex/BCD to 7 Segment Display 
STR2INT Convert String to Integer 
STR2REAL Convert String to Real 
SWAPB Swap Bytes 

Counter Boxes 
CNT Up Counter 
CNTDN Down Counter 
RSTCT - Reset Counter 
UDC - Up/Down Counter 

CTRIO Boxes 
CTAXCFG CTRIO2 Axis Configuration 
CTAXDYNP CTRIO2 Axis Run Dynamic Pos. 
CTAXLIMT CTRIO2 Axis Run Trapzd w/Limits 
CTAXTRAP CTRIO2 Axis Run Trapezoid 
CTDYNPOS CTRIO Run Dynamic Position 
CTDYNVEL CTRIO Run Dynamic Velocity 
CTREGRD CTRIO Read Register 
CTREGWR CTRIO Write Register 
CTRUNPOS CTRIO Run Position Mode 
CTRUNVEL CTRIO Run Velocity Mode 
CTTBLADD CTRIO Add Entry to Preset Table 
CTTBLEDT CTRIO Edit Preset Table Entry 
CTUPDLVL CTRIO Update Level Mode 

Date/Time/Calendar Boxes 
DT2EPOCH Convert Date/Time to Epoch 
DTCMP Compare Date/Time 
DTDIFF Difference between 2 Date/Times 
DTOFFSET Add Offset to Date/Time 
EPOCH2DT Convert Epoch to Date/Time 
SETTIME Set PLC Date/Time 

Device Boxes 
CLOSE Close Device 
DEVCLEAR Clear Device 
DEVREAD Read Device Register 
DEVWRITE Write Device Register 
OPENDEV Open Device 

Differential/Edge/Clock Boxes 
ND Trailing Edge One-Shot 
PD Leading Edge One-Shot 

Drum Boxes 
DRUM Timed/Event/Timed-Event Drum 

Ethernet Boxes 
EMAIL Send EMail 
OPENTCP Open TCP Connection 
SETUPIP Setup TCP/IP Parameters 
SETUPNOD Setup Ethernet Node Parms 
TCPLISTEN Listen on TCP Port 
UDPIN Input UDP Packet to String 
UDPOUT Output UDP Packet 

Externally Sourced Data Boxes 
PUBLISH Translate from MX 
SUBSCRIB Translate to MX 

Hardware Information Boxes 
HWINFO Get Hardware Information 

Intelligent Module Boxes 
RD Read from Intelligent Module 
WT Write to Intelligent Module 

Looping Boxes 
FOR Index Loop 
NEXT Index by Step 
REPEAT Start of Repeat/Until Loop 
UNTIL Repeat/Until Condition is Non-0 
WHILE Loop While Condition is Non-0 
WEND End While Loop 
BREAK Exit Loop 
CONTINUE Skip to Loop End 

Math Boxes 
MATH Calculate Expression 

Math-Basic Boxes 
DEC Decrement 
INC Increment 

Math-High Level Boxes 
RANDSEED Random Number Seed 

Modbus Boxes 
MRX Modbus Network Read (TCP & RTU) 
MWX Modbus Network Write (TCP & RTU) 
Process Boxes 
CLAMP Limit Range 
DEADBAND Set Outside Deadband 
FILTER First Order Filter 
INTEGRAT Integrate over Time 
PID Closed Loop Controller 
PIDINIT Set PID Tuning Constants 
RAMPSOAK Ramp/Soak Profile 
SLOPE Calculate Slope 
TIMEPROP Time Proportional Control 

Program Control Boxes 
ENTASK Enable Task 
EXIT Exit this Program 
GOTO Go To Label 
HALT Halt Program or Task 
LABEL Code Label 
RESTART Restart Program or Task 
RSTWT Reset Watchdog Timer 
RUN Run Program 
STOP Switch to Program Mode 
SUSPEND Suspend Program/Task Execution 
YIELD Yield Program/Task Execution 

Protocol Boxes 
CHECKSUM Checksum Algorithm 
STRGETB Get Bytes Out of a String 
STRPUTB Put Bytes Into a String 

Serial Port 
SETUPSER Setup Serial Port 

Shift Boxes 
ROTL Rotate Left 
ROTR Rotate Right 
SR Shift Register 

Stage Boxes 
JMP Jump to Stage 
JMPI Indexed Jump to Stage 
SG Stage (first SG is Initial SG) 
SGCONVRG Converge Multiple SGs 
SGDIVRG Jump to Multiple Stages 
SGRST Disable Stage 
SGRSTR Disable Range of Stages 
SGSET Enable Stage 

String (ASCII/Buffer) Boxes 
STRCMP String Compare 
STRFIND Find within a String 
STRIN Input String from Device 
STROUT Output String to Device 
STROUTL Output String to User Log 
STROUTS Output String to String 
STRSUB Get Sub-String 
STRTRIM Trim Whitespace 
STRTRUNC Set String Length 

Timer Boxes 
OFFDTMR Off Delay Timer 
ONDTMR On Delay Timer 
RSTT Reset Timer 
TMR Timer 
TMRA Accumulating Timer 
TMRADOWN Accumulating Time Down 
TMRDOWN Time Down 

MATH Operators & Functions 
+ - * /  Add, Subtract, Multiply, Divide 
% Modulo (Remainder) 
**  Raise to Power 
-  Negate 
&  Bitwise AND 
|  Bitwise OR 
^  Bitwise XOR 
~  Bitwise Invert 
<<  Shift Left 
>>  Shift Right 
>>>  Unsigned Shift Right 
&&  Logical AND 
||  Logical OR 
!  Logical NOT 
==  Equal To 
!=  Not Equal To 
<  Less Than 
<=  Less Than or Equal To 
>  Greater Than 
>=  Greater Than or Equal To 
ABS(exp)  Absolute Value 
ACOS(exp) Arc Cosine 
ASIN(exp)  Arc Sine  
ATAN(exp)  Arc Tangent  
AVG(start, #val)  Average of range 
COS(exp)  Cosine of radian angle 
DEG(exp)  Convert radians to degrees 
FRAC(exp) Fractional part of real 
LN(exp)  Natural Log base e 
LOG(exp)  Log base 10 
MIN(start, #val) Min. value in range 
MAX(start, #val)  Max. value in range 
NOW()  $Now 1970 Epoch value 
RAD(exp)  Convert degrees to radians 
RANDINT() Random Int 0 to 2,147,483,647 
RANDREAL()  Random Real 0.0-1.0 
ROUND(exp)  Round real number 
SIN(exp)  Sine of radian angle 
SQRT(exp) Square Root 
SUM(start, #val) Sum values in range 
TAN(exp)  Tangent of radian angle 
TICKus()  System uSec Counter Val 
TICKms()  System mSec Counter Val 
TOINT(exp) Convert Real to Integer 
TOREAL(exp)  Convert Int. to Real 
TRUNC(exp)  Truncate Real number

MX FAQ0019
Q: What do the PUBLISH and SUBSCRIB instructions do?
A: These instructions could possibly be needed when an external system is providing data or the MX-PLC is providing data to an external system and the data types do not exactly match. These instructions let you move/convert/align the data to MX memory locations. Both of these are table instructions, where for each row in the table instruction, you enter a source, destination and number of elements and the options for converting it.

Those options are:

The way it was envisioned was to stick one or more SUBSCRIB instructions in the Top of Scan task, and one or more PUBLISH instructions at the Bottom of Scan task, whose sole purpose is to move/convert data to/from 'public' memory and from/to 'internal' memory. Clean and well-bounded.

MX FAQ0020
Q: Is there an OROUT instruction (or equivalent) so that an output can be controlled from more than one ladder rung?
A: There is no OROUT instruction or an equivalent. However the functionality of an OROUT can be implemented by using the system block $TopOfScan and an RST of the output there. Then elsewhere in the program use SET of that same output.

MX FAQ0021
Q: The XRef (cross reference) only shows addresses. Can it show rung numbers instead?
A: The address that is shown is a link to the instruction that it is used in. Rung numbers map to multiple instructions. Just click on the link and it will take you to the rung and the block cursor will be overtop of the exact instruction. Once there, you can see the rung number in the margin. However, in a future version of MX we are considering keeping the link to be addressed based but the display you actually see is the rung number.

MX FAQ0022
Q: How can I clear a string (SS or SL)?
A: Use the STRTRUNC instruction and set the length to 0 (which is the default).

MX FAQ0023
Q: What is the functional equivalent to a DirectLOGIC LD (Load) instruction?
A: Use the INIT or MOVE instruction.