A telegram fixes how many 16-bit words the PLC and the G120 exchange and what each word means. For most machines choose Standard Telegram 1 (PZD-2/2): STW1 and speed setpoint out, ZSW1 and actual speed in. Choose 20 when you also need current, torque and power; 352 for PCS 7 or fault codes; 353/354 when the PLC must read or write parameters; 3 for encoder position. Select it in the G120's Device overview in TIA Portal and make sure the drive's p0922 holds the same number.
- Telegram 1 covers most conveyors, pumps and fans — start there unless you need more data.
- The TIA Portal telegram and p0922 in the drive must be the same number.
- A longer telegram uses more I/Q bytes and can move your addresses — re-check the Device overview after every change.
- The first word is always STW1 out and ZSW1 in, so your control-word logic works with every standard telegram.
Try it first: the Live PLC–VFD Simulator shows Telegram 1 running word by word in your browser.
What a Telegram Actually Is
A PROFINET telegram is an agreement between the PLC and the drive about the cyclic process data (PZD): how many words go each way and which signal sits in which word. The PLC side of the agreement lives in the TIA Portal hardware configuration; the drive side is parameter p0922. Both must name the same telegram.
Once both ends agree, the exchange runs automatically every PROFINET cycle. The PLC program never "sends" a telegram — it simply writes its Q words and reads its I words.
All G120 Telegrams at a Glance
These are the telegrams you will meet on G120 control units. Not every control unit supports every telegram — encoder telegrams, for example, need a control unit with an encoder interface such as the CU250S-2 — so always check the list of p0922 values for your control unit and firmware.
| Telegram | Name in TIA Portal | PZD out / in | PLC → drive | Drive → PLC | Typical use |
|---|---|---|---|---|---|
| 1 | Standard telegram 1 | 2 / 2 | STW1, NSOLL_A | ZSW1, NIST_A | Simple speed control — conveyors, pumps, fans |
| 2 | Standard telegram 2 | 4 / 4 | STW1, NSOLL_B (32-bit), STW2 | ZSW1, NIST_B (32-bit), ZSW2 | Higher speed resolution, sign-of-life |
| 3 | Standard telegram 3 | 5 / 9 | STW1, NSOLL_B, STW2, G1_STW | ZSW1, NIST_B, ZSW2, G1_ZSW, G1_XIST1, G1_XIST2 | Speed control with encoder position in the PLC |
| 20 | Standard telegram 20 | 2 / 6 | STW1, NSOLL_A | ZSW1, speed, current, torque, power, NAMUR word | Process industry, energy and load monitoring |
| 350 | SIEMENS telegram 350 | 4 / 4 | STW1, NSOLL_A, M_LIM, STW3 | ZSW1, speed, current, ZSW3 | Speed control with torque limit from the PLC |
| 352 | SIEMENS telegram 352 | 6 / 6 | STW1, NSOLL_A, 4 free PCS 7 words | ZSW1, speed, current, torque, WARN_CODE, FAULT_CODE | PCS 7 and DCS, fault codes on the HMI |
| 353 | SIEMENS telegram 353 | PKW + 2 / 2 | STW1, NSOLL_A | ZSW1, NIST_A_GLATT | Telegram 1 behaviour plus parameter access |
| 354 | SIEMENS telegram 354 | PKW + 6 / 6 | As 352 | As 352 | Telegram 352 plus parameter access |
| 999 | Free telegram | User-defined | Your own interconnection | Your own interconnection | Special data not covered by a standard telegram |
Word Layout of Every Telegram
The diagram shows each telegram word by word. Orange words are written by the PLC to the drive (Q area); teal words are sent by the drive to the PLC (I area). Wide cells are 32-bit values that use two words.
What each signal means
The abbreviations come from the PROFIdrive profile and Siemens drive documentation. "GLATT" means smoothed.
| Signal | Direction | Size | Meaning | Scaling |
|---|---|---|---|---|
STW1 | PLC → drive | 16 bit | Control word 1 — ON/OFF, enables, acknowledge | Bit field |
STW2 | PLC → drive | 16 bit | Control word 2 — data sets, sign-of-life | Bit field |
STW3 | PLC → drive | 16 bit | Control word 3 — additional commands | Bit field |
NSOLL_A | PLC → drive | 16 bit | Speed setpoint | 16#4000 = 100 % of p2000 |
NSOLL_B | PLC → drive | 32 bit | Speed setpoint, high resolution | 16#4000_0000 = 100 % of p2000 |
M_LIM | PLC → drive | 16 bit | Torque limit | 16#4000 = 100 % of p2003 |
G1_STW | PLC → drive | 16 bit | Encoder 1 control word | Bit field |
ZSW1 | Drive → PLC | 16 bit | Status word 1 — ready, running, fault, warning | Bit field |
ZSW2 / ZSW3 | Drive → PLC | 16 bit | Status words 2 and 3 | Bit field |
NIST_A / NIST_A_GLATT | Drive → PLC | 16 bit | Actual speed (GLATT = smoothed) | 16#4000 = 100 % of p2000 |
NIST_B | Drive → PLC | 32 bit | Actual speed, high resolution | 16#4000_0000 = 100 % of p2000 |
IAIST_GLATT | Drive → PLC | 16 bit | Actual current, smoothed | 16#4000 = 100 % of p2002 |
MIST_GLATT | Drive → PLC | 16 bit | Actual torque, smoothed | 16#4000 = 100 % of p2003 |
PIST_GLATT | Drive → PLC | 16 bit | Actual power, smoothed | 16#4000 = 100 % of r2004 |
MELD_NAMUR | Drive → PLC | 16 bit | Fault and alarm word to VIK-NAMUR | Bit field |
WARN_CODE / FAULT_CODE | Drive → PLC | 16 bit | Number of the active warning / fault | Integer code |
G1_ZSW, G1_XIST1, G1_XIST2 | Drive → PLC | 16 / 32 / 32 bit | Encoder 1 status and position values | Encoder increments |
PKW | Both | 4 words | Parameter channel — read or write any parameter | Request / response |
Which Telegram Should You Choose?
Work down the questions. The first "yes" gives you the telegram; if every answer is "no", Telegram 1 is the right choice.
Telegram 1 vs 20 vs 352
These three cover most standard-drive applications. The table shows what each one gives the PLC.
| Question | Telegram 1 | Telegram 20 | Telegram 352 |
|---|---|---|---|
| Words out / in | 2 / 2 | 2 / 6 | 6 / 6 |
| Run and speed setpoint | Yes | Yes | Yes |
| Actual speed | Yes | Yes, smoothed | Yes, smoothed |
| Actual current | — | Yes | Yes |
| Actual torque | — | Yes | Yes |
| Actual power | — | Yes | — |
| Fault / warning number | — | NAMUR bit word | Yes, as codes |
| I bytes used | 4 | 12 | 12 |
| Best for | Standard machines | Energy and load monitoring | PCS 7, DCS, HMI fault text |
Configure telegrams on real SINAMICS hardware
Set up Telegram 1, 20 and 352 on a G120 and see the data change live in TIA Portal. Pune classroom or live online.
Telegram Size and I/Q Addresses
Each PZD word takes two bytes in the PLC's process image. The telegram therefore decides how large the I and Q ranges are. The example ranges below assume TIA Portal assigned start address 256; your project may use a different start.
| Telegram | Q bytes | I bytes | Example Q range | Example I range |
|---|---|---|---|---|
| 1 | 4 | 4 | %QB256…259 | %IB256…259 |
| 2 | 8 | 8 | %QB256…263 | %IB256…263 |
| 3 | 10 | 18 | %QB256…265 | %IB256…273 |
| 20 | 4 | 12 | %QB256…259 | %IB256…267 |
| 350 | 8 | 8 | %QB256…263 | %IB256…263 |
| 352 | 12 | 12 | %QB256…267 | %IB256…267 |
| 353 | 8 PKW + 4 PZD | 8 PKW + 4 PZD | Two ranges | Two ranges |
| 354 | 8 PKW + 12 PZD | 8 PKW + 12 PZD | Two ranges | Two ranges |
Example: Telegram 20 address map
Siemens stores the high byte first, so in %IW256 the ZSW1 bits 8–15 sit in %IB256 and bits 0–7 in %IB257. For bit-level detail see SINAMICS G120 STW1 and ZSW1: Every Control and Status Bit.
Selecting the Telegram in TIA Portal
The same six steps apply to S7-1200 and S7-1500. Step 3 differs slightly depending on whether the drive was added with Startdrive or with a GSD file.
| Step | Where in TIA Portal | What to do |
|---|---|---|
| 1 | Hardware catalog → SINAMICS G120 control unit | Add the drive with the correct control unit (e.g. CU240E-2 PN) and firmware version. |
| 2 | Devices & networks → Network view | Connect the drive to the PLC's PROFINET subnet and assign it to the IO controller. |
| 3 | G120 → Device view → Device overview | Select the telegram: with Startdrive in the drive properties (Telegram configuration); with the GSD file, drag the telegram module from the catalog into the telegram slot. |
| 4 | Device overview → I address / Q address | Note the start addresses and lengths TIA Portal assigned. Change the start address here if needed. |
| 5 | Drive parameters (Startdrive or BOP-2) | Set p0922 to the same telegram number. Startdrive does this on download; with GSD set it yourself and save (RAM to ROM). |
| 6 | Online → Diagnostics | Download both, go online and confirm the drive shows no PROFINET alarm and ZSW1 is changing. |
Startdrive or GSD file?
| Startdrive | GSD file | |
|---|---|---|
| How the drive appears | Full drive object with parameters in TIA Portal | PROFINET device with telegram modules only |
| Where you select the telegram | Drive properties → Telegram configuration | Drag the telegram module into the Device overview |
| Who sets p0922 | Startdrive, on download | You — with Startdrive, BOP-2, IOP or a macro |
| Risk of mismatch | Low | Higher — two separate places to change |
| Best for | New projects with TIA Portal | Older firmware, third-party engineering, S7-300/400 |
With the GSD route, fieldbus macro p0015 = 7 sets PROFINET control with Telegram 1 as its default, which is a quick way to prepare a drive before connecting it to the PLC.
Once the telegram is set, the next step is the PLC program — see G120 PROFINET Standard FB for a reusable block built on Telegram 1.
Telegram Mismatch: Symptoms and Fixes
Most telegram problems come from changing one end and forgetting the other. Use this table to go from the symptom to the fix.
| Symptom | Likely cause | Fix |
|---|---|---|
| Drive shows A08526 — no cyclic connection | Telegram in TIA Portal and p0922 differ, or device name / IP not assigned | Match the telegram on both ends, check the PROFINET device name, download again |
| PLC shows the drive with a red error in Devices & networks | Configured module length does not fit the drive's telegram | Check the Device overview module against p0922 and the firmware version |
| Speed and current values look swapped or wrong | PLC program reads the words of a different telegram layout | Re-map the I words using the word layout for the selected telegram |
| F01910 — fieldbus setpoint timeout | Cyclic data stopped: PLC in STOP, cable, or the connection dropped after a telegram change | Restore communication, then acknowledge the fault |
| Everything worked, then I/Q addresses changed | Telegram was changed to a longer one and TIA re-assigned addresses | Update the PLC tags to the new start addresses from the Device overview |
Step-by-Step Lab: Set and Change a Telegram
Hands-on- An S7-1200 or S7-1500 and a G120 with a PROFINET control unit in one TIA Portal project, with device name and IP address assigned.
- A motor on a test bench or uncoupled.
- Estimated time: 45 minutes.
Check which telegrams your control unit supports
Look up p0922 for your control unit and firmware in the list manual, or open the drop-down in Startdrive.
Select Telegram 1
In the G120 Device view, select Standard telegram 1, PZD-2/2.
Match the drive
Download with Startdrive, or set p0922 = 1 and save if you use a GSD file.
Change to Telegram 20
Replace the telegram with Standard telegram 20, PZD-2/6 and compile.
Create the mismatch on purpose
Download the PLC only, without changing p0922.
Fix it and read the new data
Set p0922 = 20, go online and add %IW260 (current) and %IW262 (torque) to the watch table.
You understand telegram selection if you can say why Telegram 20 needs 12 I bytes but only 4 Q bytes, what happens when only one end is changed, and where to read the address ranges after a change.
Telegram choice is one decision inside Siemens PLC and VFD networking; the overview compares every connection method first.
Frequently asked questions
What is the difference between telegram 1 and telegram 20?
Both send the same two words to the drive: STW1 and the speed setpoint. Telegram 1 returns two words, ZSW1 and actual speed. Telegram 20 returns six: ZSW1, smoothed speed, current, torque, power and a NAMUR fault word — useful when the PLC must monitor load or energy.
Which telegram should I use for a simple conveyor or pump?
Standard Telegram 1, PZD-2/2. It gives run, stop, speed setpoint, status and actual speed with the smallest I/Q footprint, and it is the telegram most PLC examples and standard blocks are written for.
Does p0922 have to match the telegram in TIA Portal?
Yes. The PLC hardware configuration decides how many words are exchanged and the drive's p0922 decides what each word means. If they differ, the drive usually reports no cyclic connection, or the data arrives in the wrong words.
Why did my I and Q addresses change when I switched telegram?
A telegram with more words needs a longer address range. TIA Portal re-assigns the range when the module changes, so read the new start addresses from the Device overview and update your PLC tags.
What is PKW in telegram 353 and 354?
PKW is a parameter channel of four words in each direction. The PLC uses it to read or write any drive parameter, such as a ramp time, while the PZD words keep running the drive cyclically.
When should I use the free telegram 999?
Only when no standard telegram carries the data you need. With p0922 = 999 you interconnect each receive and send word yourself through r2050 and p2051, which is flexible but harder to document and to replace.
Why does the G120 show alarm A08526 after I changed the telegram?
A08526 means no cyclic PROFINET connection. After a telegram change it usually means only one side was updated — download the PLC hardware configuration and set the same telegram in p0922.