Mitsubishi Electronics FXavc-4DA 5.Specifications, 6.Buffer Memory (BFM), 7.Operation and Program Examples, 8.Caution Regarding Operation, 7.2 Program example, [BFM #20] Initialize

5.Specifications

5.1 General specifications

The general specifications are equivalent to those of the PLC main unit. (Refer to the FX2NC Handy Manual.)

5.2 Power supply specifications

Item	Specifications
Analog circuits	24 V DC±10%, 130 mA, externally supplied

6.Buffer Memory (BFM)

The FX2NC-4DA exchanges data with the PLC via the buffer memory addresses (16-bit data) in the FX2NC-4DA.

BFM #0 to #5, #8 to #17, #20 and #21 can be written by the PLC using the TO instruction. BFM #29 and #30 can be read using the FROM instruction.

6.1 Buffer Memories (BFM) lists

BFM No. Description

[BFM #8 and #9] Offset/gain setting command

Changes offset and gain values of channels CH1 to CH4 by writing 1 to the corresponding Hex digits of BFM #8 or #9. The current values will be valid until this command is output. (Refer to Chapter 9)

BFM #8	BFM #9
H	H
G2 O2 G1 O1	G4 O4 G3 O3

1 to 4: Channel number O = 0: No changes done. O = 1: Change data value.

7.Operation and Program Examples

If the factory-default I/O characteristics are not changed and the status information is not used, you can operate the FX2NC-4DA using the following simple program. For the FROM and TO instructions, refer to the FX Programming Manual (II).

CH1 and CH2 : Voltage output mode (-10 V to 10 V)

CH3	: Current output mode (4 mA to 20 mA)
CH4	: Current output mode (0 mA to 20 mA)

Digital circuits	5 V DC, 30 mA, supplied from the PLC main unit using an
	extension port

5.3 Performance specifications

Item	Voltage output	Current output
Analog	-10V DC to 10V DC (External	DC 0mA to 20mA (External
output range	load resistance: 2kΩ to 1MΩ).	load resistance: 500Ω or less).
Digital input	Effective numeric value	Effective numeric value
	(11 bits) + Sign (1 bit)	(10 bits) + Sign (1 bit)
Resolution	5mV (10V ⋅ 1/2000)	20∝A (20mA ⋅ 1/1000)

#0 *1	Output mode select. Factory setting H0000
#1	Output data CH1
#2	Output data CH2
#3	Output data CH3
#4	Output data CH4
#5 *1	Data holding mode. Factory setting H0000
#6, #7	Reserved
#8	Offset/gain setting command CH1, CH2 Initial value H0000
#9	Offset/gain setting command CH3, CH4 Initial value H0000

[BFM #10 to #17] Offset/gain data

The offset and gain values are changed by writing new data to BFM #10 to #17. The units of the data to be written are mV or ∝A. The data should be written and then BFM #8 and #9 set. Note that the data value will be rounded down to the nearest 5mV or 20∝A.

[BFM #20] Initialize

When K1 is written in BFM #20, all values will be returned to the factory-default. (Note that the BFM #20 data will override the BFM #21 data.)

This initialize function is convenient if you have an error in adjustment.

[BFM #21] I/O characteristics adjustment inhibit

M8002

TO K0 K0 H2100 K1

initial pulse

Write the data for CH1 to D0, CH2 to D1, CH3 to D2 and CH4 to D3.

M8000

TO K0 K1 D0 K4

RUN monitor

(H2100) → BFM #0

CH1 and CH2: Voltage output

CH3: Current output (4mA to 20 mA)

CH4: Current output (0 mA to 20 mA)

Write data in respective data registers while observing the following ranges:

Data register D0 and D1: -2,000 to 2,000

Data registers D2 and D3: 0 to 1,000

Data register D0 → BFM #1 (output to CH1) Data register D1 → BFM #2 (output to CH2) Data register D2 → BFM #3 (output to CH3) Data register D3 → BFM #4 (output to CH4)

	25°C ± 5°C; ±0.5%			25°C ± 5°C; ±0.5%
Total	(at full scale of 20V)
	0°C to 55°C; ±1.0%			(at full scale of 16mA)
accuracy				0°C to 55°C; ±1.0%
	(at full scale of 20V)
	(Excluding load fluctuation)			(at full scale of 16mA)
Conversion	2.1ms for 4 channels (A change in the number of channels
speed	used will not change the conversion speed.)
Isolated	Analog output and PLC are isolated by photocoupler. Power
	supply and analog output are isolated by transformer.
method
	(Channels are not isolated from each other.)
Number of
occupied I/O	8 points. (Including input and output points)
points
Applicable	FX2NC Series PLC
	(Up to four units can be connected including special function
PLC
	blocks and special function units connected to FX2NC-CNV-IF.)
Built-in	EEPROM
memory
	Mode 0 (Voltage output: -10V to 10V)
	At the load resistance of 10kΩ
				10.235V
			10V
		Analogoutput			2,047
	-2,000
	-2,048			2,000
				Digitalinput
				-10V
		-10.24V
I/O	Mode 1 (Current output: 4mA to 20mA)
characteristics	At the load resistance of 250Ω
(Default:		20mA
mode 0)
(I/O	Analog
characteristics
	output
can be		4mA
adjusted
using the
procedure	0			1,000
described in			Digitalinput
Section 9 in	Mode 2 (Current output: 0mA to 20mA)
this manual.)
	At the load resistance of 250Ω
		20mA
	Analog
	output

01,000

Digitalinput

A command sent from the programmable controller can change the mode. The voltage/current output mode selected will determine the output terminals used.

#10	Offset data CH1 *2
#11	Gain data CH1 *3
#12	Offset data CH2 *2	Unit: mV or ∝A
#13	Gain data CH2 *3
		Initial offset value: 0
#14	Offset data CH3 *2
		Initial gain value: 5,000 *4
#15	Gain data CH3 *3
#16	Offset data CH4 *2
#17	Gain data CH4 *3
#18,#19	Reserved
#20	Initialize. initial value = 0
#21 *1	I/O characteristics adjustment inhibit (Initial value b1=0, b0=1)
#22 to #28	Reserved
#29	Error status
#30	K3020 identification code
#31	Reserved

*1 The status of BFM #0, #5, and #21, will be written to EEPROM, therefore the set values will be retained even after turning OFF the power.

*2 Offset data:Actual analog output value when corresponding output data (BFM #1 to #4) is 0

*3 Gain data: Actual analog output value when corresponding output data (BFM #1 to #4) is 1,000

*4 When current output mode 1 (4 mA to 20 mA) is set, the offset data will be automatically set to 4,000 and the gain data to 20,000. When the current output mode 2 (0 mA to 20 mA) is set, the offset data will be automatically set to 0 and the gain data to 20,000.

[BFM #0] Output mode select

The value of BFM #0 switches the analog output between voltage and current for each channel. It takes the form of a 4 digit hexadecimal number. The first digit will be the command for channel 1 (CH1), and the second digit for channel 2 (CH2) etc. The numeric values of these four digits respectively represent the following items:

H	O = 0:Sets the voltage output mode (-10 V to 10 V).
	O = 1:Sets the current output mode (4 mA to 20 mA).
CH4CH3CH2CH1	O = 2:Sets the current output mode (0 mA to 20 mA).

Switching the output mode resets the I/O characteristics to the factory-default characteristics. Refer to the performance specifications described in section 5. Example: H2110CH1: Voltage output (-10 V to 10 V)

CH2 and CH3: Current output (4 mA to 20 mA)

CH4: Current output (0 mA to 20 mA)

[BFM #1, #2, #3 and #4] Output data channels CH1, CH2, CH3, and CH4 BFM #1: Output data of CH1 (Initial value: 0)

BFM #2: Output data of CH2 (Initial value: 0)

BFM #3: Output data of CH3 (Initial value: 0)

BFM #4: Output data of CH4 (Initial value: 0)

[BFM #5] Data holding mode

While the programmable controller is in the STOP mode, the last output value in the RUN mode will be held. To reset the value to the offset value, write the hexadecimal value in BFM #5 as follows:

H	O = 0: Holds the output.
	O = 1: Resets to the offset value.
	CH4CH3CH2CH1

Example: H0011 CH1 and CH2 = Offset value CH3 and CH4 = Output holding

Setting BFM #21 to K2 inhibits the user from inadvertent adjustment of I/O characteristics. The adjustment inhibit function, once set, will be valid until the Permit command (BFM #21=K1) is set. The initial value is K1 (Permit). The set value will be retained even after power-OFF.

[BFM #29] Error status

When an error occurs, use the FROM command to read out the details of the error.

Error status

Bit	Name	Status when bit is set to "1"	Status when bit is set
		(turned ON)	to "0" (turned OFF)
b0	Error	Error if any of b1 to b4 is turned	No error
		ON
		Offset/gain data in EEPROM is
b1	O/G error	abnormal or a data setting error	Offset/Gain data normal
		occurs.
b2	Power supply	24V DC power failure	Power supplied
	error		normally
b3	Hardware	Defective D/A converter or other	Functioning hardware
	error	hardware
b4	Program error	FROM/TO instruction is used by	Program is normal.
		mistake.
		The digital input or analog output	The input or output
b10	Range error		value is in the specified
		value is out of the specified range.
			range.
	G/O-
b12	Adjustment	BFM #21 is not set to "K1".	Adjustable status
	prohibit status

Bits b4 to b9, b11, b13 to b15 are not defined.

[BFM #30] Identification code

The identification code for a special function block is read using the FROM instruction. The identification code for the FX2NC-4DA unit is K3020.The main unit can use this facility in the program to identify the special function block before commencing any data transfers from and to the special function block.

Note:

Values of BFM #0, #5, and #21, are stored in the EEPROM memory of the FX2NC-4DA. BFM #10 to #17 are copied to EEPROM when the gain/offset setting command BFM #8, #9 is used. Also, BFM #20 causes the resetting of the EEPROM memory. The EEPROM has a life of about 10,000 cycles (changes), so do not use programs which frequently change these BFMs.

A mode change of BFM #0 automatically involves a change of the corresponding offset and gain values. Because of the time needed to write the new values to the internal EEPROM memory, a delay of 3 s is required between instructions changing BFM #0 and instructions writing to the corresponding BFM #10 through BFM #17.

Therefore, a delay timer should be used before writing to BFM #10 through #17. (Refer to chapter 9.)

7.1 Operation procedure

1)Turn OFF the power of the PLC, and then connect the FX2NC-4DA. After wards, wire the I/O lines of the FX2NC-4DA.

2)Set the PLC to STOP, and turn ON the power. Write the above program then switch the PLC to RUN.

3)Analog values will be sent from D0 (BFM #1), D1 (BFM #2), D2 (BFM #3), and D3 (BFM #4) to the respective output channels of the FX2NC- 4DA. When the PLC is in STOP, the analog values set before stopping the PLC will remain output. (The output will be held.)

4)When the PLC is in STOP, the offset values can also be output. For a detailed description, refer to Section 6).

7.2 Program example

In the example shown below, CH1 and CH2 in the FX2NC-4DA, connected to the special function block No. 0, are handled as the voltage output, CH3 is handled as the current output (4 to 20 mA), CH4 is handled as the current output (0 to 20 mA), and these outputs are held when the PLC is stopped. In the example shown below, the status information is utilized.

M8000	FROM		K0	K30	D4	K1
							BFM #30 (model code) of the
RUN							block No. 0 → Transferred to D4.
monitor	CMP		K3020	D4	M0		When the code No. is K3020
M1							(FX2NC-4DA), M1 turns ON.
							H2100 → BFM #0 (unit No. 0)
	TO	P	K0	K0	H2100	K1
							CH1 and CH2: Voltage output
	Writes -2,000 to 2,000 to D0 and D1.						CH3: Current output (4 to 20 mA)
	Writes 0 to 1,000 to D2 and D3.						CH4: Current output (0 to 20 mA)
							D0 → BFM #1 (CH1 output)
			K0	K1	D0	K4	D1	→ BFM #2 (CH2 output)
							D2	→ BFM #3 (CH3 output)
	FROM		K0	K29	K4M10	K1	D3	→ BFM #4 (CH4 output)
M10							BFM #29 (b15 to b0) →
			M20
					M3		M10 to M25
							The status information is read.
No error	Normal output range
							The output data is normal.

8.Caution Regarding Operation

1)Check whether the output wiring and/or the FX2NC-4DA is properly connected to the FX2NC main unit.

2)The FX2NC-4DA uses 30mA (5V) supplied from the main unit.

Confirm that the total value including the 5V current consumption of other special function blocks is less than the limit.

3)The FX2NC-4DA starts operation when the 24V DC power is set to ON. Make such a program that changes over the output of the BFM #0 before writing the output data.

4)After the 24V DC power for the FX2NC-4DA is turned ON or OFF, the analog output may fluctuate for approximately 1 second. This is due to time delays in the power supply from the main unit or differences in start time. For this reason, be sure to take preventive measures so that this output fluctuation will not affect the external units.

[Example of preventive measure]

	Powerswitch	Analogdata
		cutOFFcircuit
24VDCpower	FX2NC-4DAspecial	External
supply	functionblock	analogunit