Frequently Asked Questions for S7-300（3）
41: What should I pay attention to when I / O is accessed directly?It is important to note that in an S7-300 configuration, if a direct read access is made to the I / O across the module (read several bytes at once)
It will read the incorrect value. You can view the specific address through hardw are.
42: Does the SM321 module need to be connected to DC 24V?
Not required, if the MLFB is 6ES7 321-1BH02-0AA0 SM 321 module, no longer need to connect DC 24V.
43: How do I plan the simulation module SM374 in the STEP 7 hardware configuration? How do I find this module in the hardware catalog?
The analog module SM374 can be used in three modes: as a 16-channel digital input module, as a 16-channel digital output module,
8 inputs and 8 outputs of mixed digital input / output modules.
Now the SM374 in accordance with the module you need to simulate to configure, that is;
If the SM 374 is used as a 16-channel input module, configure a 16-channel input module - Recommended: SM 321: 6
ES7321-1BH01-0AA0,
If the SM 374 is used as a 16-channel output module, configure a 16-channel output module - Recommended: SM 322:
6ES7322-1BH01-0AA0,
If the SM 374 is used as a mixed input / output module, configure a mixed input / output module (8 inputs, 8 outputs)
Recommended: SM 323: 6ES7323-1BH01-0AA0.
44: Is the analog input I + of module 6ES7 331-1KF0.-0AB0 destroyed when the sensor is short-circuited when measuring current?
When measuring the current, the sensor short circuit occurs, the module 6ES7 331-1KF0.-0A B0 analog input I + will not be destroyed. The module
With built-in overcurrent protection. > Each 50 ohm resistor in the module has a PTC element in front to prevent the input channel of the module from being
damage.
Note that the input voltage allows a long-term maximum of 12V and a short (up to 1 second) value of 30V.
45: If the CPU is cut off, does the 2-wire measuring transmitter continue to supply power?
If the transmitter module is inserted in position "D" and the module is supplied with an external voltage from pin 1 and pin 20, the 2-wire measurement transmitter continues
Electricity. Even if the CPU is cut off, its supply current remains unchanged.
46: When using the S7-300 analog input module to measure the temperature (Fahrenheit), can you use the absolute error limits listed in the module documentation?
You can not use the specified error limit directly. The basic error and operating error are stated in absolute temperature and in degrees Celsius. Must be multiplied by a factor of 1.8
Convert it to fahrenheit temperature units.
Example: S7-300 AI 8 x RTD: The specified temperature input operation error is +/- 1.0 degrees Celsius. When measured at Fahrenheit, the maximum acceptable
The error is +/- 1.8 degrees Fahrenheit.
47: Why can I use a commercial digital multimeter to read a constant current for reading an impedance on an analog input block?
Almost all of the S5 / S7 analog input devices still work in a complex manner, that is, all channels are inserted into the only one AD conversion
On the device. The principle also applies to the constant current necessary to read the impedance. Therefore, the current flowing through the resistor is only used for short-term reading. For there is one
The selected interface suppresses "50Hz" and 8 parameterized channels of SM331-7KF02-0AB0, which means that the current will flow about once every 180ms
There are 20ms readable impedance.
48: Why is the voltage output of the S7-300 analog output group out of tolerance? What are the terminals S + and S use?
The following description applies to all analog output modules SM 332:
When using the analog output module SM 332, care must be taken to return the inputs of inputs S + and S. They are used to compensate for the purpose of performance impedance. When used
When an independent conductor with S + and S is connected to the two contacts of the actuator, the analog output adjusts the output voltage so that the actual operation of the actuator
The voltage is the desired voltage.
If you want to get compensation, then the actuator must be connected with four wires. This means that for the first channel, you need:
The output voltage is connected to the actuator via pin 3 and pin 6.
Assign the actuator pin 4 and pin 5.
If you do not want to get compensated, simply cross the pins 3-4 and pins 5-6 on the front switch.
Note: The output voltage is adjusted to a maximum of 140 mV (for 10V) due to the open sensor terminals (S + and S-). g for this
Assigned, can not maintain 0.5% of the voltage output using the error limit.
49: How to connect a potentiometer to 6ES7 331-1KF0-0AB0?
The sampling end and the head end of the potentiometer are connected to M +, the terminals are connected to M- and S and M- are connected together.
Note: The maximum possible resistance is 6K. If the potentiometer supports direct output of a variable voltage, then the head of the potentiometer should be connected to V +
M-side connection M-.
50: How do I connect a PT100 temperature sensor to the analog input module SM331?
PT100 thermal resistance varies with the temperature of its resistance value changes. If there is a constant current flowing through the thermal resistance, the thermal resistance drops on the voltage
With temperature. A constant current is applied to the contacts Ic + and Ic-. The analog module SM331 changes the current at M + and M- By measuring electricity
Pressure can determine the temperature.
PT100 to analog input group There are three types of connections: 4-wire connection for the most accurate measurement.
note:
1) The formula for 3-wire connection only indicates the actuality of the analog input module SM331 (MLFB number 6ES7 331-7Kxxx-0AB0) b "
Determination of the process.
2) In the S7-300 series, there are some analog inputs that have been measured multiple times. They prescribe the line resistance of the common return line and make a mathematical supplement
Compensation. The accuracy of the connection is almost 4 lines. An example of such a module is SM331 (MLFB No. 6ES7 331-7PF00-0A B0).
3) the formula is still applicable to the main physical relationship, but does not include the determination of PT100 resistance of the effective measurement process.
51: Can I connect a HART measurement converter to a SIMA TIC S7-300 series of conventional analog input modules?
If you do not need other HA RT features of the HA RT measurement converter, you can also use other S7-300 analog input modules. For example, you can
Use module 6ES7 331-7KF0x-0AB0 or an isolated 4-channel module (eg 6ES7 331-7RD00-0AB0). For this, will be integrated
Should be set to 16.66ms, 20ms or 100ms. For connection to a hand-held device, or with a handheld device, the circuit must be connected in series
250- Ohm resistance.
Note: If you want to program a HA RT measurement converter via a controller (say, SIMA TIC PDM), you must use a corresponding
HA RT module (for example, 6ES7 331-7TB00-0AB0 or 6ES7 332-5TB00-0AB0).
52: How to avoid fluctuations in the analog input in the SM335 module? The following wiring instructions are suitable for the following MLFB analog input / output modules: 6ES7335-7HG00-0AB0, 6ES7335-7HG01-0AB0 Check whether an ungrounded sensor installed on an insulated rack or check that your sensor is grounded. Sensors mounted on insulated racks: Connect the ground terminal Mana (pin 6) to the measuring channel M0 (pin 10), M1 (pin 12), as far as possible through the shortest path (if possible, directly connected to the front connector) M2 (pin 14) and M 3 (pin 16) and central ground (CGP). Grounding sensor: Make sure the sensor has a good equipotential bonding. And then isolate the connection from M to Mana and to the central ground. Place the shield on both sides.
53: Can I use the error check and standard modules together in the central rack in the S7-300F? On the central rack of the S7-300F, error-proof and non-error-proof (standard) digital E / A modules can be mixed. For this reason, as in the ET200M, an isolation module (MLFB: 6ES7195-7KF00-0XA0) is required to isolate the error prevention module and the standard module in the central and expansion racks. Observe the following installation guidelines: The standard module (IM, SM, FM, CP) must be inserted into the slot on the left side of the isolation module. The error-proof digital E / A module must be inserted into the slot on the right side of the isolation module.
54: Can the sensor / actuator from explosion-proof area 0 or explosion-proof zone 1 be connected directly to the S7-300 Ex (i) module? Can not connect sensor / actuator from explosion proof zone 0. But can be directly connected from the explosion-proof area 1 sensor / actuator. Ex (i) modules are tested according to [EEx ib] IIC. Therefore, there are two explosion-proof barriers on the module. However, you must obtain [EEx ia] approval to use the sensor / actuator from the explosion area 0. (The module should have three explosion-proof barrier).
55: Use FM 355 or FM 355-2 in SIMATIC PCS 7 What should you pay special attention to? For example, if you want to use the FM 355 or FM 355-2 in a redundant ET 200M station, note the following important points: There are two function blocks available for connecting the FM 355. For example, you can use the advanced features of the IM 153-2 HF interface module with order no. 6ES7 153-2BA00- 0XB0 if you need to use the "Replace module during operation" (hot swap) function. In this case, you must activate the "Replace module in run" (hot swap) function when configuring with the "Hardware configuration" software. The IM 153-2 and all SM / FM / CPs are plugged into the active bus module (order no. 6ES7 195-7Hxxx-0XA0).
56: What are the precautions when the output of the first FM 352-5 is directly connected to the input of the second FM 352-5? If you want to interconnect the two FM352-5, 6ES7 352-5A H10-0A E0 (P-type sink output) can be achieved. 6ES7 352-5A H00-0A E0 M-type sink output, this output is only available at each output when a plug-in resistor is available, the recommended pull-out resistor specifications: 2,2 kOhm / 0,5 W. Make sure There is a short circuit connection in the switch box. In this case the operating frequency can be as high as 100 kHz.
57: Can I replace the FM353 / FM354 without a PG? can. FM353 (MLFB No. 6ES7 353-1A H01-0A E0) and FM354 (MLFB No. 6ES7 354-1A H01-0A E0) can be replaced without PG. Requirements: Use the configuration kit FM353 V2.1 or the configuration package FM354 V2.1 and STEP 7 version V3.1 or higher. Procedure: After completing the FM and system startup, you must create a system data block (SDB> = 1000) and store it on the PG. All parameterized data (DB / traverse program, machine data, incremental dimension table, etc.) of FM are stored in this SDB. Transfer this SDB to the CPU or transfer it to the CPU's memory card.
57: How do I directly read count and measured values by accessing I / O on the FM 350-2? FM 350-2 allows up to four count values or measured values to be displayed directly on the module I / O. You can define which individual measurement values to display in the I / O area by using the "Specify Channel" function. Depending on the size of the count value or the measured value, the data format parameter must be changed to "Word" or "Dw ord" in the "User type". If the parameter is "Dw ord", each "user type" can have only one count value or measured value. If the parameter is "Word", you can read two values. In the user program, the command L PIW is used for Word access, and the L PID is used for Dw ord access.
58: How should I connect the Siemens 6FX2001-5 (Up = 24V; SSI) absolute encoder? 59: FM357 -2 What should you pay attention to when using an absolute encoder? The firmware version of the FM357-2 is V3.2 / V3.3 The sampling value of the absolute encoder may be incorrect in the following cases. The FM357- 2 firmware version is V3 .4 these problems will be resolved. 1) FM357-2 failed to start. For example, the power is turned off within the time defined in the startup window. 2) FM357-2 pull in operation
