YOKOGAWA Power Series Plus IM 249x-COMM Use and care manual

Communications Power SeriesPlus
Manual
Power SeriesPlus
Digital Switchboard Meter
IM 249x-COMM
1
IM 249x-COMM
Revision 1, October 1999

CONTENTS
TABLE OF CONTENTS
IM 249x-COMM
1ST edition, October 1999
All Rights Reserved, Copyright 1999, Yokogawa Corporation of America 0
Introduction...............................................................................................................1
YCA Protocol ............................................................................................................2
Getting Current Settings and Display...............................................................3
Changing Settings ...........................................................................................3
Unit Responses and Error Codes....................................................................7
Modbus Protocol......................................................................................................8
Function Codes................................................................................................8
Register Table .................................................................................................9
Exception Codes............................................................................................13
Changing Modbus Settings............................................................................13
Misc. Notes on Modbus.................................................................................14
Hardware Connections ..........................................................................................15

1. INTRODUCTION
1. INTRODUCTION
IM 249x-COMM 1
The Power SeriesPlus Digital Switchboard Meter has many settings that can be
changed by the user. These settings can be displayed and changed by using the
four (4) keys, also called pushbuttons, on its front panel. The user can also
perform all these same changes over an RS-485 2-wire serial connection. You
can read and change all the settings and read all measurements.
You can choose one of two available protocols for communications – YCA or
Modbus (available only on 2493).
YCA protocol is a simple master-slave ASCII-based protocol. Almost any
communications software will work with it.
Modicon developed Modbus. It is a popular protocol used in many control
systems.
Note:
1) When a unit is ordered from the factory, the communications protocol must be
selected. The protocol type is not field selectable.
2) MODBUS protocol is only available on 2493 models.

2. YCA Protocol
2. YCA PROTOCOL
IM 249x-COMM 2
This is a protocol developed by YCA. It uses ASCII characters. All units act as
slaves in a master-slave network. There is no broadcast option.
The communications settings for the software are as follows:
Baud Rate: 9600, 4800, 2400 or 1200 bps (set using the front panel)
8 Data Bits, 1 Stop Bit, No Parity.
To communicate with the unit over a serial line the following string is sent:
<stx> <COMMAND><SP> <ADDRESS><SP> <FUNCTION><SP> <parameters> <CR> <etx>
•The special characters ‘stx’ and ‘etx’ are standard communications codes and
most software will insert them automatically. ‘CR’ stands for ‘Carriage
Return’, also referred to as ‘Enter’. ‘SP’ stands for the ‘Space’ character.
•The COMMAND can be one of two choices:
‘DG’ - to get settings
‘DP’ - to change settings
•The ADDRESS is a two-digit number from 01 to 32. The address can only be
changed from the front panel.
Each unit in a network must have a unique number for communications to
work. The default on all units is ‘01’.
•The FUNCTION is one of the following codes:
(Note: The functions available depend on the particular model)
Code Function
PT - Potential Transformer Ratio
CT - Current Transformer Ratio
OUT1 - Analog Output for upper (or single) display (upper limit, zero offset & center)
OUT2 - Analog Output for second display (if there is one (2492/2493 only))
OUT3 - Analog Output for third display (if there is one (2493 only))
AVG - Sample Average for all displays
LOCK - disables/Enables the keys
DISP - Show the latest measurement(s) (works only with the ‘DG’ command.)
F - Gives the model code (‘DG’ only)
MIN - Show or reset minimum measurement(s) (2493 only)
MAX - Show or reset maximum measurement(s) (2493 only)
LL - Line-to-line voltages or line-to neutral (Voltmeters only) (2493 only)
•The parameters are dependent on the function. They are not needed when
the command is ‘DG’, only for ‘DP’. See the section “ Changing Settings ” for
an explanation of all the parameters.

2. YCA Protocol
IM 249x-COMM 3
Getting Current Settings and Display
To get the current setting value, or to see what’s on the display, use the format:
DG aa bbbb <CR>
Where ‘aa’ is the address of the unit (01 - 32) and
‘bbbb’ is the code of the function as shown above.
Remember to put a space between each word.
For example, to get the present potential transformer setting from unit 21 send -
DG 21 PT <ENTER>
The unit will respond with a string of numbers. The format is shown below in
“ Changing Settings ”.
Changing Settings
To change a setting send an ASCII string in the format:
DP aa bbbb xxxxxxxxx <CR>
‘aa’ is the address.
‘bbbb’ is the code of the function.
‘xxxxxxxxx’ are the new settings (parameters). The format is described below.
Potential Transformer DP aa PT xxxxxy/xxx
The part before the slash is the value that you want to make the primary side of
the transformer. This could be in volts (e.g. 960.0) or in terms of the ratio (e.g.
8). It can be up to four (4) digits with or without a decimal point. If you put more
than four digits you will get an error message.
The ‘y’ is where you can put a multiplier that corresponds to the LEDs under the
display. If you put a ‘K’ it multiplies the value by 1,000. An ‘M’ will multiply by
1,000,000. You can omit it if there is no multiplier (i.e. multiplied by 1).
After the slash put the value you desire for the secondary side. This can be
120/240 volts depending on the model, or ‘1’ for a simple ratio. If you enter
anything except a ‘1’ the unit will default to the voltage value (120 or 240).

2. YCA Protocol
IM 249x-COMM 4
Examples: To set a 120V voltmeter PT to a 1:1 ratio you can enter:
DP 01 PT 120/120 or DP 01 PT 1/1
To set it to 120:1 you would enter:
DP 01 PT 120/1 or DP 01 PT 14.4K/120 o r DP 01 PT .12K/1
Note that you cannot put 14400/120 because you can only have 4 digits on the
left side.
Once you enter your new ratio, the unit will echo your entry with a question mark.
For example:
01 PT 14.4K/120 ?
Within ten seconds you need to enter
DP 01 OK
If you enter a valid ratio the unit will respond
01 DONE
If you exceed the ratio limits (for PT that is <1:1 or >1250:1) or make some other
mistake you will get an error message such as:
01 ERR 6C
The error codes are explained under the “ Unit Responses and Error Codes ”
section.
Current Transformer DP aa CT xxxxxy/x
Same format as PT. If you have a 1 Amp unit you don’t get a choice for the
secondary value. It will always be ‘1’. You can leave it blank if you like, but don’t
forget the ‘/’. If you have a 5 Amp unit, the secondary can be ‘1’ or ‘5’.
Analog Output DP aa OUT1 xxxxxy/±xxxxxy/x or
DP aa OUT2 xxxxxx/±xxxxxy/x (for the second channel) or
DP aa OUT3 xxxxxx/±xxxxxy/x (for the third channel)
The first section (before the first slash) is for the upper limit, or ‘HI’ setting.

2. YCA Protocol
IM 249x-COMM 5
Up to four digits with an optional decimal point and an optional multiplier.
The second section is for the zero offset, or ‘LO’ setting. It has the same format
as ‘HI’ with the addition of a plus or minus sign at the beginning. If the sign is
omitted it defaults to plus.
Note: Both the LO and HI values are based on the primary side of the PT and
CT and will change proportionally if the PT or CT settings are changed.
The last digit is for the ‘Center’ setting. There are only two choices:
‘0’ for 0 to 1mA or ‘1’ for -1 to 1mA.
Voltmeters, ammeters and any meters using 4-20mA output do not have a
-1to1mA CENTER option.
For example, if you wish to set a voltmeter with 0-1 milliamps output to send out1
mA when the input voltage is 160V and 0 mA when the input is 0 you would
enter:
DP 01 OUT1 160/0/0 (HI = 160, LO=0, CENTER=0 to 1)
If you want a wattmeter with -1to1 mA output to give max output (+1mA) when
the input is 15050 Watts and minimum output (-1mA) when the input is -15065
Watts you would enter:
DP 01 OUT1 15.05K/-7.5/1
For HI you can’t put ‘15050’ because that is more than four digits. When
CENTER is -1to1 then LO becomes the halfway point between minimum and
maximum output, so -7.5 is halfway between 15050 and -15065.
Special Note : for VAR and Power Factor meters, ‘Lead’ is shown as a negative
value and ‘Lag’ is shown as a positive value.
Sample Average DP aa AVG xx
‘xx’: number of samples taken before displaying measurement. Valid values
are 00 to 29. Must always be two digits. If you want to set the unit to eight
samples enter ‘08’ not ‘8’.
Key Lock DP aa LOCK
This will disable the buttons on the front panel. No parameter is necessary to
change this setting. When you send the ‘DP’ command it will just change to the
opposite setting. Lock >> unlock or unlock >> lock.

2. YCA Protocol
IM 249x-COMM 6
If you send a ‘DG’ command it will respond with 1 for locked or 0 for unlocked.
Model Code DG aa F
This command will get the model code from the unit. You cannot use it to
change the model code. The code is in the format
8abc0ddd (the ‘8’ is a constant. It will never change.)
a - Inputs Measured :
0 - Volts 9 – DUAL – Volts/Hertz
1 - Amps A – DUAL - Watts/VARs
2 - Watts B – DUAL - Watts/Power Factor
3 - VARs C – TRIPLE – Volt/Volt/Volt
5- Power Factor D – TRIPLE – Amp/Amp/Amp
6 - Phase Angle E – TRIPLE – Volt/Amp/Hertz
7 – Hertz F – TRIPLE – Watt/VAR/PF
8 – DUAL - Volts/Amps
b - Input Frequency :
0 - 45-65 Hertz
1 - 400 Hertz
c - Input Source : 0 - 1P2W, 120V, 1A (W/VAR/PF)
or
150V (V/Hz) or 1 Amp
1 - 1P2W, 240V (W/VAR/PF) or
300V (V/Hz) or 1 Amp
2 - 1P2W, 120V, 5A or 5 A
3 - 1P2W, 240V, 5A
4 - 1P3W or 3P3W, 120V, 1A
5 - 1P3W or 3P3W, 240V, 1A
6 - 1P3W or 3P3W, 120V, 5A
7 - 1P3W or 3P3W, 240V, 5A
8 - 3P4W, 120V, 1A
9 - 3P4W, 240V, 1A
A - 3P4W, 120V, 5A
B - 3P4W, 240V, 5A
d - Analog Output : 1 - 0 to 1mA
2 - -1 to 1 mA
3 - 4 - 20 mA

2. YCA Protocol
IM 249x-COMM 7
Unit Responses and Error Codes
The unit will always respond to any message addressed to it. If you send a
‘DG...’ and it is a legitimate request the response will be the setting value you
requested. Some other responses are:
SYN ! When the function code is not recognized.
N/A ! When the function code does not apply to this model. (e.g. using
‘CT’ on a Volt/Frequency meter. Or ‘OUT1’ on a unit with no
analog output.)
TMER ! When you send a ‘DP’ message to change a setting, you must
confirm it within ten (10) seconds, or the change is discarded and
the unit replies with this.
DONE When a change has been made successfully.
ERR xxx When a change was not successful. The ‘xxx’ gives the reason for
the failure as listed below.
ERROR CODES
CT*PT - The combined ratio of PT and CT is too large
LO - The value entered is too low
HI - The value entered is too high
SPAN - Output span is too small or too large
MIN - Output span exceeds low limit
PARAM - Invalid parameter value
EEPROM - EEPROM write error (return for repair)
UNK - Unknown error

3. MODBUS Protocol
3. MODBUS PROTOCOL (Available on 2493 models only)
IM 249x-COMM 8
Modbus is an open communications protocol developed by Modicon Inc. to
connect controllers and other devices over a network. It defines a standard way
of passing messages between devices so that they will be able to parse an
incoming message and take any appropriate action necessary.
Devices communicate using a master-slave technique, in which only one device
(the master) can initiate transactions (called ‘queries’). The other devices (the
slaves) respond by supplying the requested data to the master, or by taking the
action requested in the query. The master can address individual slaves, or can
initiate a broadcast message to all slaves. Slaves return a message (called a
‘response’) to queries that are addressed to them individually. Responses are
not returned to broadcast queries.
The Power SeriesPlus always acts as a slave in accordance with The Modicon
Modbus Reference Guide PI-MBUS-300. It has the following characteristics:
Interface: RS-485
Transmission modes: ASCII (7 data bits) or RTU (8 data bits). Both use 2
stop bits
Parity: even, odd, or no parity
Baud Rate: 9600, 4800, 2400 or 1200 bps
The default settings from the factory are RTU mode, no parity, 9600 bps.
Function Codes:
The following function codes are supported:
03 – Read Holding Registers
04 – Read Input Registers
The device will respond to either of these codes in the exact same way. They
were both included to allow compatibility with a wider range of systems. You can
read any single register or the following sets of registers:
1 thru 14 - all the settings, except output ranges
22 thru 36 - all the output range settings
37 thru 50, 67 thru 80, 97 thru 110 – Latest, Minimums and Maximums for
Volts, Amps and Frequency
51 thru 56, 81 thru 86, 111 thru 116 – Latest, Minimums and Maximums
for Watts, VARs, and Power Factor