Configuring NTP Time Synchronization on Siemens TP1500 Comfort Panels Over Long Distances

Overview

Time synchronization of SIMATIC TP1500 Comfort panels distributed across a plant floor requires careful attention to transport protocol, network topology, and master clock selection. The TP1500 Comfort is a 15" widescreen HMI panel from the SIMATIC HMI Comfort family, designed for high-end machine-level visualization. Unlike Basic Panels, the Comfort line supports NTP (Network Time Protocol) client operation and can also receive time forwarded by a SIMATIC S7 PLC acting as a slave on an S7 connection.

This reference covers synchronizing up to four TP1500 Comfort panels to a Windows 10 PC acting as the time source, addressing the common concern about whether physical distance between master and slave (up to 2 km in the field) affects synchronization accuracy. It also documents the daylight-saving-time (DST) limitation of Comfort panels and the supported forwarding architecture via S7-1500 / S7-1200 / S7-300 / S7-400 PLCs.

Prerequisites

Before configuring time synchronization, confirm the following hardware and software items are in place.

• TP1500 Comfort (6AV2 124-1QB01-0AX0 or current equivalent) firmware version 16.0 or later. NTP client support is available on all Comfort panels from V14 SP1 onward, but the V16 / V17 / V18 / V19 / V20 firmware trains are recommended for new deployments.
• TIA Portal V17, V18, V19, or V20 with the HMI Comfort Panel HSP (Hardware Support Package) installed. Project view must be on the matching firmware target so that the Time synchronization editor exposes the correct fields.
• SIMATIC S7 PLC (S7-1200, S7-1500, S7-300 with CP, or S7-400) acting as the time master to the panels if the PC cannot be addressed directly on the same Ethernet subnet. The PLC itself must be an NTP client of the Windows 10 PC.
• Windows 10 PC running an NTP server. The built-in w32time service can serve time on UDP/123, or a third-party NTP server such as Meinberg NTP or Chrony for Windows can be used for stratum-1 accuracy when an external reference is required.
• Ethernet network between the PC and the PLC, and a separate Ethernet or PROFINET segment between the PLC and the TP1500 panels. The maximum distance of 2 km is feasible with copper (100 m per segment) plus fiber media converters or switches, or with PROFINET over fiber for a single 2 km run.
• Firewall rules on the Windows 10 PC permitting inbound UDP/123 from the PLC / panel IP addresses, and outbound responses.

Reference Architecture: PC → PLC → TP1500 Comfort

The most reliable and Siemens-recommended topology for plant-wide time distribution is:

[ Windows 10 PC                ]
[  NTP server (stratum 1/2)    ]
[  UDP 123                     ]
        │
        │ Ethernet (≤ 100 m copper per hop)
        ▼
[ SIMATIC S7-1500 CPU         ]
[  NTP client (synchronized)  ]
[  PLC RTC = local civil time ]
[  DST handled by CPU clock   ]
        │
        │ PROFINET / Ethernet (S7 connection)
        │ up to 2 km via fiber
        ▼
[ TP1500 Comfort #1 ]   [ TP1500 Comfort #2 ]   [ TP1500 #3 ]   [ TP1500 #4 ]
[  Time-of-day slave ]  [  Time-of-day slave ] [  ...       ] [  ...      ]

This arrangement gives every device a consistent civil time, including DST, and is the architecture recommended in the TIA Portal help for Configuring time synchronization for integrated connections for Comfort Panels.

A direct NTP link from the PC to each TP1500 Comfort is technically possible if the PC and all four panels share a routed IP path with UDP/123 open in both directions. This avoids the PLC in the loop but requires careful firewall configuration, and the Comfort panel's DST bit will not toggle automatically — the PC must push the DST-adjusted time as civil time, which is what NTP does by default.

Effect of Distance on NTP Synchronization

The original concern in the field case was whether a 2 km separation between the Windows NTP server and the TP1500 Comfort panels degrades time accuracy. The short answer is: no, not at any practical plant scale.

NTP synchronization accuracy is dominated by the round-trip delay between client and server, not by the absolute one-way path length. The relevant figures:

The NTP algorithm in the TP1500 Comfort firmware selects eight time samples per polling cycle, filters out network jitter, and converges on the median offset. As long as the round-trip delay is below roughly 100 ms (which it always is on a 2 km plant segment) the synchronization is well within the algorithm's correction range and the panel clock will track the master to within tens of milliseconds.

TIA Portal Configuration: Integrated Connection

For an integrated S7 connection where the TP1500 Comfort talks to a SIMATIC PLC and the PLC is the time source, configure the HMI as a time slave on the S7 channel. Refer to the official TIA Portal help topic: Configuring time synchronization for integrated connections in the TIA Portal V20 online help.

Step-by-step: PC NTP → S7-1500 → TP1500

1. In the TIA Portal project tree, open Devices & Networks and select the S7-1500 CPU.
2. In the CPU properties, navigate to Properties > Time of day > Time synchronization.
3. Set Time source to NTP server. Activate Synchronize with NTP server.
4. Enter the Windows 10 PC IP address (for example 192.168.10.5) as the primary NTP server. Optionally enter a secondary server for redundancy.
5. Set Update interval to 10 s (the minimum on S7-1500). Smaller intervals increase network traffic; 10 s is a good balance.
6. Confirm the CPU's time zone is configured. In Properties > Time of day > Time zone, set the local time zone and enable Daylight saving / standard time so the CPU itself flips the DST bit.
7. Compile and download the CPU configuration.
8. Now select the TP1500 Comfort in the project tree. In its properties, open Connections > [the S7 connection to the CPU] > Time synchronization.
9. Activate Acquire time from PLC (or the equivalent label in your TIA Portal version). This sets the panel's Time-of-day slave role.
10. Compile and download the panel project. Repeat for all four TP1500 Comfort devices, reusing the same S7 connection point if a single CPU serves multiple panels.

After download, the panel receives the PLC's civil time (UTC offset + DST) on the configured polling interval. The PLC in turn is NTP-locked to the Windows 10 PC, giving the entire chain a coherent time base.

Direct NTP Configuration on the TP1500 Comfort

If you prefer to skip the PLC and have the TP1500 Comforts synchronize directly to the PC, follow this procedure.

1. In the TIA Portal project, select the TP1500 Comfort device.
2. Open Properties > Time of day > Time synchronization (the exact navigation may differ slightly between TIA V17, V18, V19 and V20 — the path is Runtime settings > Time synchronization in some versions).
3. Enable Time synchronization via NTP.
4. Set the Update interval to 16 s or 64 s. Shorter intervals keep tighter lock but increase UDP traffic.
5. Enter the Windows 10 PC IP as the NTP server address.
6. Configure the Time zone on the panel to match the local civil time. Enable Daylight saving time if you want the panel to apply DST itself; the NTP stream from the PC delivers UTC, and the panel will convert to local civil time using the zone and DST rules.
7. Download the configuration. Restart the HMI runtime so the new NTP settings take effect.

On the Windows 10 PC, configure w32time or a third-party NTP daemon to listen on UDP/123. The minimal command sequence in an elevated command prompt is:

w32tm /config /manualpeerlist:"192.168.10.5,0x9" /syncfromflags:manual /reliable:YES /update
net stop w32time & net start w32time
w32tm /query /status

Verify the service is advertising on UDP/123 with netstat -ano | findstr :123. Open Windows Firewall inbound rule UDP 123 for the NTP source profile.

Daylight Saving Time Handling

The Comfort panel firmware does not perform the spring/fall DST flip on its own. The following behavior applies:

• If the panel is set to time-of-day slave on an S7 connection, it accepts whatever time the PLC pushes, including DST adjustments that the S7-1500 / S7-1200 CPU handles natively.
• If the panel is set to NTP client, it converts the received UTC into local civil time using its own time-zone and DST rules, which must be configured on the panel. This is self-consistent as long as the panel's DST rules match the plant's civil definition.
• Panels set to no synchronization rely on the local RTC, which drifts by a few seconds per day and will not flip DST automatically.

When the plant is split across jurisdictions or has shift patterns that ignore DST, document the convention in the TIA Portal project notes so future engineers do not change it.

Configuration Parameter Reference

Verification

After commissioning, validate that all four TP1500 Comfort panels are displaying the same civil time to within ±1 second. Use this procedure.

1. On the Windows 10 PC, run w32tm /query /status and confirm Source: shows a stratum-1 or stratum-2 reference and Last Successful Sync Time: is recent.
2. On the S7-1500 (if used), open the online diagnostics in TIA Portal and view Online & Diagnostics > Time of day. The displayed local time should match the PC to within a few tens of milliseconds.
3. On each TP1500 Comfort, open Control Panel > System > Time and Date. The panel should display the same civil time as the PLC, including the correct DST offset.
4. For a stress test, force a step change on the PC (set the time forward by 1 minute via date / time or by stopping and restarting w32time) and observe that all four panels track the new value within one to two polling intervals.
5. For a distance / latency test, use the NTP utility built into the panel's diagnostic page (or a Windows w32tm /monitor against the panel IP if the panel exposes its NTP state) and confirm round-trip delay is well under 100 ms.

Troubleshooting Matrix

Alternative: External NTP Reference on the PC

If the plant requires traceable time (e.g. for 21 CFR Part 11 or audit logs), point the Windows 10 PC at a public or GPS-backed NTP source and re-distribute from there. Common options:

• GPS / DCF77 receiver connected to the PC via USB or serial, driving w32time or a Meinberg NTP daemon. The PC then becomes a stratum-1 server for the plant.
• Public NTP pool (e.g. pool.ntp.org) for non-critical machines. Avoid for audit-relevant timestamping.
• Siemens SICLOCK GPS-based time generator, installed on the plant network as a dedicated time source. The S7-1500 and the TP1500 Comforts can both be configured to use SICLOCK as their NTP server.

Security Considerations

NTP on UDP/123 is unauthenticated by default on most Comfort panel firmware versions. On a segregated plant LAN this is acceptable; on a network shared with office traffic, consider:

• Disabling NTP server mode on every device that does not need to be a master.
• Using NTP Authentication (Symmetric Key, MD5) where both the PC daemon and the S7-1500 CPU support it. S7-1500 supports NTP authentication from firmware V2.6 onward.
• Restricting NTP traffic to a dedicated VLAN with ACLs on the managed switches (SCALANCE XC-200 / XR-100 / XM-400).

FAQ