I'm stumped! 90/30 and operator key pad

[CalG]

For those who have looked on before, this is a continuation.

A process tool that sat for some time in storage.

A GE 90/30 311 to control the pumps, valves, and process sequence.

A KEP MMI-200 24 key operator. (NO Display! Only key pads and LEDs)

On first power up while in a recommission process, the operator panel displays all the signs of a lost memory. That is, no connection with the plc and no project to be retrieved from the unit. (programming software from KEP)

"Factory suggested" Diagnostics indicatet a bad MMI-200 unit. Ahh the ravages of time.

'Sent the unit of to KEP for a once over. Returned with a new memory chip.

Refitted the unit to the tool....Exactly the same results as at first. No connectivity with the plc. Indicator lights consistent with not communication with plc

In the mean time, I have become more familiar with the 90/30 and the LM90 application. The machine works fine!, The logic/project for the 90/30 preserved in EEPROM.
But,....I have NO record of the MMI-200 project. It should not be too complicated as the interface is ONLY buttons, momentary too, if I read the logic correctly. (set bit on)

I have fitted a second serial port module (Horner XXX,,,,900) and that works fine. ( Thanks to contributions from forum members!) With that added card, I can monitor any changes that a key entry from the panel might make. There are none ;-(.

I must be missing something basic.

I have made a MMI project and loaded it into the unit. Verification returns positive. I even pulled the project from the unit into a new project to confirm that everything proceeded as intended. A- OK.

Please be advised, I have no clue about what is right, Nothing to compare to and no examples to look at. I'm only going on my "reading" of the ladder logic and trying to get the operator to do what is readily accomplished in the LM90 program. That is, perform all the programmed functions! ;-)

I've assigned the keys to the %Mxxxx references as displayed in the ladder logic. I'm not sure if this is correct. Perhaps I should be writing the keyboard presses to internal memory (%Rxxxx)

Since the %M references are not working with the MMI-220 even though toggling them in the LM90 program works a charm, It makes me look elsewhere.
What caught my eye was the final instruction in the "MANUAL MODE" block. It is a "MOVE WORD" instruction (len 2) that takes its input from LED1 (%M0505) and outputs to %R0001. The location of all the LED status bits. And registers that are set to zero on "FRST_SCAN"

32 bits being more than enough to accommodate the 24 keys available.


Looking at the MMI-200 programming software, when "write to " is selected for the key stroke operation the value entry window prompts with four zeros. IS this a suggestion to enter the entire LED status word in Hex?

AM I way off base?

You might know, bits, bytes. words, dwords arrays and strings might as well be so much babble. I read and re read, but it goes in and out untouched. I'm good at a few other things however ;-)

Examples and guidance welcome!

Cheers

Cal

 

[jrwb4gbm]

You probably already have the manual but if not, I found this:
Link:
http://www.kep.com/support/manuals/plc/99582%20MMI-2XX.pdf

 

[Eric Nelson]

I've assigned the keys to the %Mxxxx references

Do you simply assign a single starting address, or can you specify each key independently?

If you only need to assign a single address, then (based on the original thread) I'm betting that if you assign this starting address to be %R0001, everything will work.



-Eric

 

[Steve Bailey]

Tell me more about the cable between the KEP unit and the PLC. The manual shows the port as RS232. The port on the PLC power supply is RS485.

Is there anything about the port setup in the KEP software? The default setting for the PLC port is 19200 baud, odd parity.

 

[CalG]

Single starting address for the LED's seems right

The LEDs start at %M0505, a word boundary and continue sequentially through to %M0528. These references are confirmed in the Printed ladder logic listing.

When setting up a key in the software, references and descriptions are entered independently. Any Key can be assigned to any %I, %T, %M, %Q, %R etc. reference.

But, I'm not quite clear of your suggestion.



And yes, I have the manual, I wish it helped ;-)

Do you simply assign a single starting address, or can you specify each key independently?

If you only need to assign a single address, then (based on the original thread) I'm betting that if you assign this starting address to be %R0001, everything will work.



-Eric

 

[CalG]

Tell me more about the cable between the KEP unit and the PLC. The manual shows the port as RS232. The port on the PLC power supply is RS485.

Is there anything about the port setup in the KEP software? The default setting for the PLC port is 19200 baud, odd parity.

Steve

The cable between is suspect. It is the original KEP part. Part numbers agree with the application.

There is a small circuit board midway along, I checked continuity from pins to board terminals at both ends. No broken wires. (I should have sent the cable with the panel when it was in for the factory check up. stupid on my part)
Baud rate, parity etc. is determined when the PLC and MMI-200 are selected in the MMI software project set up. No choices!


I did inquire about test procedures for the cable. (there are several capacitors that could age. They "look good" however) No response from KEP however.

I hate to throw good money after this obsolete panel, It would do the job if it only worked ;-) As mentioned, Only 20+ key positions covers everything this machine will do.

 

[Steve Bailey]

The small circuit board midway along will be the RS232/RS485 converter. From the KEP manual it looks like it gets its power from pin 6 of the KEP unit.

Baud rate, parity etc. is determined when the PLC and MMI-200 are selected in the MMI software project set up. No choices!

Does it at least tell you what baud rate and parity it uses? If you can't change the KEP settings you'll need to make sure the PLC port matches.

 

[CalG]

If I could understand just waht is being said here, I would be on to something.

extract:

[The MMI-2xx series also allows the keypad to turn on a bit in a specific register in
the PLC when a key is depressed. When keypad downloading is enabled and a
key is pressed, the key's corresponding bit is turned ON in the PLC. When the
key is released, the bit is restored to the OFF state.
Depending on the LED register chosen, the keypad status is downloaded to the
second and third registers directly after the LED register. These registers are
referred to as the LED Register+2 and LED Register+3 under Keypad Download in
the Specifications in Section 5.0. See that section for the key to bit relationship]

end extract

 

[CalG]

From my reading, the 90/30 default is 19,200, 8. odd < that is, SNP.

The small circuit board midway along will be the RS232/RS485 converter. From the KEP manual it looks like it gets its power from pin 6 of the KEP unit.

Does it at least tell you what baud rate and parity it uses? If you can't change the KEP settings you'll need to make sure the PLC port matches.

Serial port settings in the KEP software only apply to communication with the programming PC, and that is set at the PC port.
I see no settings for the Units communication with the PLC. I used the help search function on both "SERIAL" and "BAUD". No topics returned.

I see no place in the MMISoft application to do anything with communication settings. The SMIC port, and the serial port are entirely seperat, and in fact, communication through the serial port can not be made if the SMIC port CABLE is attached. Something to do with sensing.... seems odd. There is no trouble talking to the MMI 200 with the PC.

Port settings on the 90/30 are default 19200,odd,1

Of interest, is that the device is "assumed" to work as fitted, It just lost all it's history/memory.

 

[CalG]

The small circuit board midway along will be the RS232/RS485 converter. From the KEP manual it looks like it gets its power from pin 6 of the KEP unit.

Does it at least tell you what baud rate and parity it uses? If you can't change the KEP settings you'll need to make sure the PLC port matches.

Steve

The cable is NOT a straight RS232 by RS 485 converter. I have those as well to connect the PC to the plc.

According to KEP technical, there is a loop back in the panel to plc cable as well as where the power comes from.

I'm not sure about the significance of these details.

An aside,

I purchased a RS232/rs485 cable from "china cables .com"

20 bucks! and it works every bit as well as the "domestic" cable I purchased "just in case". In fact, they may be the same cable! sure look the same. You don;t suppose those crafty Asians are buying the local product at a high price, then selling it for less than half, and STILL making a killing ...including postage?! What a scam! ;-)

 

[Eric Nelson]

But, I'm not quite clear of your suggestion.

You can disregard my suggestion because:

When setting up a key in the software, references and descriptions are entered independently. Any Key can be assigned to any %I, %T, %M, %Q, %R etc. reference.

I think the primary issue now is communication between the keypad and PLC. Steve will get to the bottom of this!... :site:



-Eric

 

[CalG]

SMIC port voltage between pins at the MMI 9 pin connector

From PIN 6* to pins 1,2*,3*,7,and 8* is +4.97V
From PIN 6* to pin 4 +14.3V
from PIN 6* to pins 5*, and 9* 0V

* denotes pins present in the mating SEMIC GE90 cable assembly plug

in case this helps ;=)

 

[CalG]

Additional Cable performance observations:

I pulled out the Tek 465 o-scope to have a look at the rs485 converter output.
It appears that there are signals coming out of the SMIC cable assembly.

A led breakout (25 pin) shows strobe on pin 3
constant on on pin 6
and constant on ona pin labeled "RD" (I thought pin 3 was RD)

Using a 7 led break out , RD and DSR are illuminated with RD strobing about once in two seconds.

With the scope, I have two pairs of wires with a 60mega hz sine wave. each at 5 Volt amplitude.

One pair is constant between 2V-7.5VDC, and the other pair that coincides with the strobe between .5V and 5.5VDC.

The MMI_200 outputs straight DC

This suggests to me that the converter is working , though I can not say how well.

There is NO difference in LED breakout indications if the plc is connected or not.
And, there is No change on the o-scope trace when buttons are pressed on the keypad. The signals do follow power on and off of the MMI-200. So that's a good sign.

That really puzzles me.

I wish all electronics were as well documented as the Tek 465 is ;-) I've had to fix that twice over the years, and now the DM44 Multimeter is acting up. I guess I don't use it enough.

 

[CalG]

In closing

There was a defect in the conversion chip in the connection cable.

The 10Volt inverter section had ceased to do it's part.

A replacement chip ($1.75 + postage) and a bit of soldering has the communication link established.

On to the key assignments! "set bit" is not the right action, I'll try "toggle"

My appreciation for the prodding and insight!

Cal